Ios 如何在Swift中调整图像大小？

我正在使用Swift和Parse.com为iOS制作一个应用程序

我试图让用户从图像选择器中选择一张图片，然后在上传到我的后端之前将所选图像的大小调整为200x200像素

Parse.com有一个名为“AnyPic”的Instagram复制应用程序的教程，其中给出了调整图像大小的代码，但它是Objective-C

// Resize the image to be square (what is shown in the preview)
UIImage *resizedImage = [anImage resizedImageWithContentMode:UIViewContentModeScaleAspectFit
        bounds:CGSizeMake(560.0f, 560.0f)
        interpolationQuality:kCGInterpolationHigh];
// Create a thumbnail and add a corner radius for use in table views
UIImage *thumbnailImage = [anImage thumbnailImage:86.0f
        transparentBorder:0.0f
        cornerRadius:10.0f
        interpolationQuality:kCGInterpolationDefault];

如何在Swift中创建所选图片的200x200px版本（然后上传？

还有，thumbnailImage函数在做什么？

有关详细信息，请参阅我的博客文章

swift中的图像调整功能如下所示

func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage? {
    let size = image.size
    
    let widthRatio  = targetSize.width  / size.width
    let heightRatio = targetSize.height / size.height
    
    // Figure out what our orientation is, and use that to form the rectangle
    var newSize: CGSize
    if(widthRatio > heightRatio) {
        newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
    } else {
        newSize = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
    }
    
    // This is the rect that we've calculated out and this is what is actually used below
    let rect = CGRect(origin: .zero, size: newSize)
    
    // Actually do the resizing to the rect using the ImageContext stuff
    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    image.draw(in: rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    
    return newImage
}

使用上述功能，调整图像大小为200*200，如下代码所示

self.resizeImage(UIImage(named: "yourImageName")!, targetSize: CGSizeMake(200.0, 200.0))

swift3已更新

 func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
    let size = image.size
    
    let widthRatio  = targetSize.width  / size.width
    let heightRatio = targetSize.height / size.height
    
    // Figure out what our orientation is, and use that to form the rectangle
    var newSize: CGSize
    if(widthRatio > heightRatio) {
        newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
    } else {
        newSize = CGSize(width: size.width * widthRatio,  height: size.height * widthRatio)
    }
    
    // This is the rect that we've calculated out and this is what is actually used below
    let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
    
    // Actually do the resizing to the rect using the ImageContext stuff
    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    image.draw(in: rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    
    return newImage!
}

let image1 = resizeimage(image: myimage.image!, withSize: CGSize(width:200, height: 200))

---

因为@KiritModi的答案是2015年的，所以这是Swift 3.0的版本：

func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
    let size = image.size

    let widthRatio  = targetSize.width  / image.size.width
    let heightRatio = targetSize.height / image.size.height

    // Figure out what our orientation is, and use that to form the rectangle
    var newSize: CGSize
    if(widthRatio > heightRatio) {
        newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
    } else {
        newSize = CGSize(width: size.width * widthRatio,  height: size.height * widthRatio)
    }

    // This is the rect that we've calculated out and this is what is actually used below
    let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)

    // Actually do the resizing to the rect using the ImageContext stuff
    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    image.draw(in: rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage!
}

---

也可以使用AlamofireImage（）

---

上一篇文章中的函数给了我一个模糊的结果。

Swift 3版本和扩展样式

func resizeimage(image:UIImage,withSize:CGSize) -> UIImage {
        var actualHeight:CGFloat = image.size.height
        var actualWidth:CGFloat = image.size.width
        let maxHeight:CGFloat = withSize.height
        let maxWidth:CGFloat = withSize.width
        var imgRatio:CGFloat = actualWidth/actualHeight
        let maxRatio:CGFloat = maxWidth/maxHeight
        let compressionQuality = 0.5
        if (actualHeight>maxHeight||actualWidth>maxWidth) {
            if (imgRatio<maxRatio){
                //adjust width according to maxHeight
                imgRatio = maxHeight/actualHeight
                actualWidth = imgRatio * actualWidth
                actualHeight = maxHeight
            }else if(imgRatio>maxRatio){
                // adjust height according to maxWidth
                imgRatio = maxWidth/actualWidth
                actualHeight = imgRatio * actualHeight
                actualWidth = maxWidth
            }else{
                actualHeight = maxHeight
                actualWidth = maxWidth
            }
        }
        let rec:CGRect = CGRect(x:0.0,y:0.0,width:actualWidth,height:actualHeight)
        UIGraphicsBeginImageContext(rec.size)
        image.draw(in: rec)
        let image:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        let imageData = UIImageJPEGRepresentation(image, CGFloat(compressionQuality))
        UIGraphicsEndImageContext()
        let resizedimage = UIImage(data: imageData!)
        return resizedimage!
    }

这个答案来自@Kirit Modi

extension UIImage {

    func resizeImage(targetSize: CGSize) -> UIImage {
        let size = self.size

        let widthRatio  = targetSize.width  / size.width
        let heightRatio = targetSize.height / size.height

        // Figure out what our orientation is, and use that to form the rectangle
        var newSize: CGSize
        if(widthRatio > heightRatio) {
            newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
        } else {
            newSize = CGSize(width: size.width * widthRatio,  height: size.height * widthRatio)
        }

        // This is the rect that we've calculated out and this is what is actually used below
        let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)

        // Actually do the resizing to the rect using the ImageContext stuff
        UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
        self.draw(in: rect)
        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage!
    }
}

---

这里有两个简单的

UIImage

扩展函数：

func scaledWithMaxWidthOrHeightValue(value: CGFloat) -> UIImage? {

    let width = self.size.width
    let height = self.size.height

    let ratio = width/height

    var newWidth = value
    var newHeight = value

    if ratio > 1 {
        newWidth = width * (newHeight/height)
    } else {
        newHeight = height * (newWidth/width)
    }

    UIGraphicsBeginImageContextWithOptions(CGSize(width: newWidth, height: newHeight), false, 0)

    draw(in: CGRect(x: 0, y: 0, width: newWidth, height: newHeight))

    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return image
}

func scaled(withScale scale: CGFloat) -> UIImage? {

    let size = CGSize(width: self.size.width * scale, height: self.size.height * scale)

    UIGraphicsBeginImageContextWithOptions(size, false, 0)

    draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))

    let image = UIGraphicsGetImageFromCurrentImageContext()

    UIGraphicsEndImageContext()

    return image
}

---

例如，图像最小化为1024或更少

func resizeImage（图像：UIImage）->UIImage{

    if image.size.height >= 1024 && image.size.width >= 1024 {

        UIGraphicsBeginImageContext(CGSize(width:1024, height:1024))
        image.draw(in: CGRect(x:0, y:0, width:1024, height:1024))

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage!

    }
    else if image.size.height >= 1024 && image.size.width < 1024
    {

        UIGraphicsBeginImageContext(CGSize(width:image.size.width, height:1024))
        image.draw(in: CGRect(x:0, y:0, width:image.size.width, height:1024))

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage!

    }
    else if image.size.width >= 1024 && image.size.height < 1024
    {

        UIGraphicsBeginImageContext(CGSize(width:1024, height:image.size.height))
        image.draw(in: CGRect(x:0, y:0, width:1024, height:image.size.height))

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage!

    }
    else
    {
        return image
    }

}

如果image.size.height>=1024&&image.size.width>=1024{
UIGraphicsBeginImageContext（CGSize（宽：1024，高：1024））
绘图（in:CGRect（x:0，y:0，宽度：1024，高度：1024））
让newImage=UIGraphicsGetImageFromCurrentImageContext（）
UIGraphicsSendImageContext（）
返回新图像！
}
否则，如果image.size.height>=1024&&image.size.width<1024
{
UIGraphicsBeginImageContext（CGSize（宽度：image.size.width，高度：1024））
image.draw（in:CGRect（x:0，y:0，width:image.size.width，height:1024））
让newImage=UIGraphicsGetImageFromCurrentImageContext（）
UIGraphicsSendImageContext（）
返回新图像！
}
否则，如果image.size.width>=1024&&image.size.height<1024
{
UIGraphicsBeginImageContext（CGSize（宽度：1024，高度：image.size.height））
绘图（in:CGRect（x:0，y:0，宽度：1024，高度：image.size.height））
让newImage=UIGraphicsGetImageFromCurrentImageContext（）
UIGraphicsSendImageContext（）
返回新图像！
}
其他的
{
返回图像
}
}

适用于Swift 4.0和iOS 10

    extension UIImage {
        func resizeImage(_ dimension: CGFloat, opaque: Bool, contentMode: UIViewContentMode = .scaleAspectFit) -> UIImage {
            var width: CGFloat
            var height: CGFloat
            var newImage: UIImage

            let size = self.size
            let aspectRatio =  size.width/size.height

            switch contentMode {
                case .scaleAspectFit:
                    if aspectRatio > 1 {                            // Landscape image
                        width = dimension
                        height = dimension / aspectRatio
                    } else {                                        // Portrait image
                        height = dimension
                        width = dimension * aspectRatio
                    }

            default:
                fatalError("UIIMage.resizeToFit(): FATAL: Unimplemented ContentMode")
            }

            if #available(iOS 10.0, *) {
                let renderFormat = UIGraphicsImageRendererFormat.default()
                renderFormat.opaque = opaque
                let renderer = UIGraphicsImageRenderer(size: CGSize(width: width, height: height), format: renderFormat)
                newImage = renderer.image {
                    (context) in
                    self.draw(in: CGRect(x: 0, y: 0, width: width, height: height))
                }
            } else {
                UIGraphicsBeginImageContextWithOptions(CGSize(width: width, height: height), opaque, 0)
                    self.draw(in: CGRect(x: 0, y: 0, width: width, height: height))
                    newImage = UIGraphicsGetImageFromCurrentImageContext()!
                UIGraphicsEndImageContext()
            }

            return newImage
        }
    }

---

您可以在Swift 3上使用此功能进行fit图像

extension UIImage {
    func resizedImage(newSize: CGSize) -> UIImage {
        // Guard newSize is different
        guard self.size != newSize else { return self }

        UIGraphicsBeginImageContextWithOptions(newSize, false, 0.0);
        self.draw(in: CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height))
        let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return newImage
    }

    func resizedImageWithinRect(rectSize: CGSize) -> UIImage {
        let widthFactor = size.width / rectSize.width
        let heightFactor = size.height / rectSize.height

        var resizeFactor = widthFactor
        if size.height > size.width {
            resizeFactor = heightFactor
        }

        let newSize = CGSize(width: size.width/resizeFactor, height: size.height/resizeFactor)
        let resized = resizedImage(newSize: newSize)
        return resized
    }
}

用法

let resizedImage = image.resizedImageWithinRect(rectSize: CGSize(width: 1900, height: 1900))

---

对于Swift 4，我只需要在UIImage上做一个扩展，并引用self

import UIKit
extension UIImage {
  func resizeImage(targetSize: CGSize) -> UIImage {
    let size = self.size
    let widthRatio  = targetSize.width  / size.width
    let heightRatio = targetSize.height / size.height
    let newSize = widthRatio > heightRatio ?  CGSize(width: size.width * heightRatio, height: size.height * heightRatio) : CGSize(width: size.width * widthRatio,  height: size.height * widthRatio)
    let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)

    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    self.draw(in: rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage!
  }
}

---

Swift 4版本

extension UIImage {
    func resizeImage(_ newSize: CGSize) -> UIImage? {
        func isSameSize(_ newSize: CGSize) -> Bool {
            return size == newSize
        }

        func scaleImage(_ newSize: CGSize) -> UIImage? {
            func getScaledRect(_ newSize: CGSize) -> CGRect {
                let ratio   = max(newSize.width / size.width, newSize.height / size.height)
                let width   = size.width * ratio
                let height  = size.height * ratio
                return CGRect(x: 0, y: 0, width: width, height: height)
            }

            func _scaleImage(_ scaledRect: CGRect) -> UIImage? {
                UIGraphicsBeginImageContextWithOptions(scaledRect.size, false, 0.0);
                draw(in: scaledRect)
                let image = UIGraphicsGetImageFromCurrentImageContext() ?? UIImage()
                UIGraphicsEndImageContext()
                return image
            }
            return _scaleImage(getScaledRect(newSize))
        }

        return isSameSize(newSize) ? self : scaleImage(newSize)!
    }
}

---

Swift 4，扩展版，边缘无白线。

似乎没有人提到，如果使用非整数值调用

image.draw（）

，结果图像可能会在右边缘或下边缘显示白线伪影

extension UIImage {

    func scaled(with scale: CGFloat) -> UIImage? {
        // size has to be integer, otherwise it could get white lines
        let size = CGSize(width: floor(self.size.width * scale), height: floor(self.size.height * scale))
        UIGraphicsBeginImageContext(size)
        draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image
    }

---

调用resizeimage方法

 func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
    let size = image.size
    
    let widthRatio  = targetSize.width  / size.width
    let heightRatio = targetSize.height / size.height
    
    // Figure out what our orientation is, and use that to form the rectangle
    var newSize: CGSize
    if(widthRatio > heightRatio) {
        newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
    } else {
        newSize = CGSize(width: size.width * widthRatio,  height: size.height * widthRatio)
    }
    
    // This is the rect that we've calculated out and this is what is actually used below
    let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
    
    // Actually do the resizing to the rect using the ImageContext stuff
    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    image.draw(in: rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    
    return newImage!
}

let image1 = resizeimage(image: myimage.image!, withSize: CGSize(width:200, height: 200))

调整图像大小的方法

func resizeimage(image:UIImage,withSize:CGSize) -> UIImage {
        var actualHeight:CGFloat = image.size.height
        var actualWidth:CGFloat = image.size.width
        let maxHeight:CGFloat = withSize.height
        let maxWidth:CGFloat = withSize.width
        var imgRatio:CGFloat = actualWidth/actualHeight
        let maxRatio:CGFloat = maxWidth/maxHeight
        let compressionQuality = 0.5
        if (actualHeight>maxHeight||actualWidth>maxWidth) {
            if (imgRatio<maxRatio){
                //adjust width according to maxHeight
                imgRatio = maxHeight/actualHeight
                actualWidth = imgRatio * actualWidth
                actualHeight = maxHeight
            }else if(imgRatio>maxRatio){
                // adjust height according to maxWidth
                imgRatio = maxWidth/actualWidth
                actualHeight = imgRatio * actualHeight
                actualWidth = maxWidth
            }else{
                actualHeight = maxHeight
                actualWidth = maxWidth
            }
        }
        let rec:CGRect = CGRect(x:0.0,y:0.0,width:actualWidth,height:actualHeight)
        UIGraphicsBeginImageContext(rec.size)
        image.draw(in: rec)
        let image:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        let imageData = UIImageJPEGRepresentation(image, CGFloat(compressionQuality))
        UIGraphicsEndImageContext()
        let resizedimage = UIImage(data: imageData!)
        return resizedimage!
    }

func resizeimage（图像：UIImage，大小：CGSize）->UIImage{
变量实际高度：CGFloat=image.size.height
var actualWidth:CGFloat=image.size.width
设maxHeight:CGFloat=withSize.height
设maxWidth:CGFloat=withSize.width
变量imgRatio:CGFloat=实际宽度/实际高度
设maxRatio:CGFloat=maxWidth/maxHeight
让压缩质量=0.5
如果（实际高度>最大高度| |实际宽度>最大宽度）{
if（放大倍率）{
//根据maxWidth调整高度
imgRatio=最大宽度/实际宽度
实际高度=绝对高度*实际高度
实际宽度=最大宽度
}否则{
实际高度=最大高度
实际宽度=最大宽度
}
}
设rec:CGRect=CGRect（x:0.0，y:0.0，宽度：实际宽度，高度：实际高度）
UIGraphicsBeginImageContext（rec.size）
image.draw（in:rec）
让image:UIImage=UIGraphicsGetImageFromCurrentImageContext（）！
设imageData=UIImageJPEG表示（图像，CGFloat（压缩质量））
UIGraphicsSendImageContext（）
让resizedimage=UIImage（数据：imageData！）
返回resizedimage！
}

Swift 4解决方案-

使用此功能

func image(with image: UIImage, scaledTo newSize: CGSize) -> UIImage {
    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    image.draw(in: CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height))
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    drawingImageView.image = newImage
    return newImage ?? UIImage()
}

调用函数：-

image(with: predictionImage, scaledTo: CGSize(width: 28.0, height: 28.0)

---

此处28.0是您要设置的像素大小

Swift 4.2版本的@KiritModi answer

func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
    let size = image.size

    let widthRatio  = targetSize.width  / size.width
    let heightRatio = targetSize.height / size.height

    var newSize: CGSize
    if(widthRatio > heightRatio) {
        newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
    } else {
        newSize = CGSize(width: size.width * widthRatio, height: size.height *      widthRatio)
    }

    let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)

    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    image.draw(in: rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage!
}

细节

• 代码10.2.1（10E1001），Swift 5

链接

解决方案 测试功能

输出 这里有一个通用的方法（在Swift 5中）用于缩小图像的尺寸以适应大小。生成的图像可以与原始图像具有相同的纵横比，也可以是以原始图像为中心的目标大小。如果图像小于目标大小，则不会调整其大小

extension UIImage {
    func scaledDown(into size:CGSize, centered:Bool = false) -> UIImage {
        var (targetWidth, targetHeight) = (self.size.width, self.size.height)
        var (scaleW, scaleH) = (1 as CGFloat, 1 as CGFloat)
        if targetWidth > size.width {
            scaleW = size.width/targetWidth
        }
        if targetHeight > size.height {
            scaleH = size.height/targetHeight
        }
        let scale = min(scaleW,scaleH)
        targetWidth *= scale; targetHeight *= scale
        let sz = CGSize(width:targetWidth, height:targetHeight)
        if !centered {
            return UIGraphicsImageRenderer(size:sz).image { _ in
                self.draw(in:CGRect(origin:.zero, size:sz))
            }
        }
        let x = (size.width - targetWidth)/2
        let y = (size.height - targetHeight)/2
        let origin = CGPoint(x:x,y:y)
        return UIGraphicsImageRenderer(size:size).image { _ in
            self.draw(in:CGRect(origin:origin, size:sz))
        }
    }
}

---

在这里输入我的已接受答案的版本，以便与Swift 5配合使用。此解决方案不会强制展开生成的图像，从而使其更安全、更干净

扩展UIImage{ 公共函数大小调整（目标：CGSize）->UIImage{ let比率=最小值( target.height/size.height、target.width/size.width ) 让new=CGSize( 宽度：size.width*比率，高度：size.height*比率 ) UIGraphicsBeginImageContextWithOptions（新的、错误的、1.0） 绘图（输入：CGRect（原点：零，大小：新）） 延迟{UIGraphicsSendImageContext（）} 返回UIGraphicsGetImageFromCurrentImageContext（） } }

---

UIImage分机Swift 5

extension UIImage {
    func resize(_ width: CGFloat, _ height:CGFloat) -> UIImage? {
        let widthRatio  = width / size.width
        let heightRatio = height / size.height
        let ratio = widthRatio > heightRatio ? heightRatio : widthRatio
        let newSize = CGSize(width: size.width * ratio, height: size.height * ratio)
        let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
        UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
        self.draw(in: rect)
        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return newImage
    }
}

---

使用：

---

UIImage（）.resize（200300）

到目前为止，所有列出的答案似乎都会导致图像的大小减小，但大小不是以像素为单位测量的。这是一个基于像素的Swift 5调整大小

extension UIImage {
    func resize(_ max_size: CGFloat) -> UIImage {
        // adjust for device pixel density
        let max_size_pixels = max_size / UIScreen.main.scale
        // work out aspect ratio
        let aspectRatio =  size.width/size.height
        // variables for storing calculated data
        var width: CGFloat
        var height: CGFloat
        var newImage: UIImage
        if aspectRatio > 1 {
            // landscape
            width = max_size_pixels
            height = max_size_pixels / aspectRatio
        } else {
            // portrait
            height = max_size_pixels
            width = max_size_pixels * aspectRatio
        }
        // create an image renderer of the correct size
        let renderer = UIGraphicsImageRenderer(size: CGSize(width: width, height: height), format: UIGraphicsImageRendererFormat.default())
        // render the image
        newImage = renderer.image {
            (context) in
            self.draw(in: CGRect(x: 0, y: 0, width: width, height: height))
        }
        // return the image
        return newImage
    }
} 

用法：

image.resize(500)

适用于Swift 5.0 a

extension UIImage {
    func resize(_ max_size: CGFloat) -> UIImage {
        // adjust for device pixel density
        let max_size_pixels = max_size / UIScreen.main.scale
        // work out aspect ratio
        let aspectRatio =  size.width/size.height
        // variables for storing calculated data
        var width: CGFloat
        var height: CGFloat
        var newImage: UIImage
        if aspectRatio > 1 {
            // landscape
            width = max_size_pixels
            height = max_size_pixels / aspectRatio
        } else {
            // portrait
            height = max_size_pixels
            width = max_size_pixels * aspectRatio
        }
        // create an image renderer of the correct size
        let renderer = UIGraphicsImageRenderer(size: CGSize(width: width, height: height), format: UIGraphicsImageRendererFormat.default())
        // render the image
        newImage = renderer.image {
            (context) in
            self.draw(in: CGRect(x: 0, y: 0, width: width, height: height))
        }
        // return the image
        return newImage
    }
} 

image.resize(500)

extension UIImage {
    func imageResized(to size: CGSize) -> UIImage {
        return UIGraphicsImageRenderer(size: size).image { _ in
            draw(in: CGRect(origin: .zero, size: size))
        }
    }
}

let image = #imageLiteral(resourceName: "ic_search")
cell!.search.image = image.imageResized(to: cell!.search.frame.size)

extension UIImage {
    func resized(to newSize: CGSize) -> UIImage {
        return UIGraphicsImageRenderer(size: newSize).image { _ in
            let hScale = newSize.height / size.height
            let vScale = newSize.width / size.width
            let scale = max(hScale, vScale) // scaleToFill
            let resizeSize = CGSize(width: size.width*scale, height: size.height*scale)
            var middle = CGPoint.zero
            if resizeSize.width > newSize.width {
                middle.x -= (resizeSize.width-newSize.width)/2.0
            }
            if resizeSize.height > newSize.height {
                middle.y -= (resizeSize.height-newSize.height)/2.0
            }
            
            draw(in: CGRect(origin: middle, size: resizeSize))
        }
    }
}

func resizeimage(image:UIImage,withSize:CGSize) -> UIImage {
    var actualHeight:CGFloat = image.size.height
    var actualWidth:CGFloat = image.size.width
    let maxHeight:CGFloat = withSize.height
    let maxWidth:CGFloat = withSize.width
    var imgRatio:CGFloat = actualWidth/actualHeight
    let maxRatio:CGFloat = maxWidth/maxHeight
    let compressionQuality = 0.5
    if (actualHeight>maxHeight||actualWidth>maxWidth) {
        if (imgRatio<maxRatio){
            //adjust width according to maxHeight
            imgRatio = maxHeight/actualHeight
            actualWidth = floor(imgRatio * actualWidth)
            actualHeight = maxHeight
        }else if(imgRatio>maxRatio){
            // adjust height according to maxWidth
            imgRatio = maxWidth/actualWidth
            actualHeight = imgRatio * actualHeight
            actualWidth = maxWidth
        }else{
            actualHeight = maxHeight
            actualWidth = maxWidth
        }
    }
    let rec:CGRect = CGRect(x:0.0,y:0.0,width:actualWidth,height:actualHeight)
    UIGraphicsBeginImageContext(rec.size)
    image.draw(in: rec)
    let image:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    let imageData = UIImageJPEGRepresentation(image, CGFloat(compressionQuality))
    UIGraphicsEndImageContext()
    let resizedimage = UIImage(data: imageData!)
    return resizedimage!
}