Ios 如何在Swift中设置图像的宽度和高度

一般来说，

Swift

和

iOS

编程的新手。我不知道如何设置图像的宽度和高度。
比如说,

  let backgroundImage = UIImage(named: "background.png")

谢谢，我的建议很好

您应该设置

UIImageView

的大小，然后将此图像放在其上，而不是设置图像的大小，这样，图像的大小将根据您的要求显示

诸如此类

var imageView = UIImageView(frame: CGRectMake(100, 150, 150, 150)); // set as you want
var image = UIImage(named: "myImage.png");
imageView.image = image;
self.view.addSubview(imageView);

---

你有这个代码，这个代码设置宽度和高度并保存相同的位置

/**
Resize UIImageView
:param: UImage
:param: new size CGSize
:return: new UImage rezised
*/
    func imageResize (#image:UIImage, sizeChange:CGSize)-> UIImage{

        let hasAlpha = true
        let scale: CGFloat = 0.0 // Use scale factor of main screen

        // Create a Drawing Environment (which will render to a bitmap image, later)
        UIGraphicsBeginImageContextWithOptions(sizeChange, !hasAlpha, scale)

        image.drawInRect(CGRect(origin: CGPointZero, size: sizeChange))

        let scaledImage = UIGraphicsGetImageFromCurrentImageContext()

        // Clean up the Drawing Environment (created above)
        UIGraphicsEndImageContext()

        return scaledImage
    }

     let size = CGSizeMake(100, 150)

    myImageView.image! = imageResize(myImageView.image!,sizeChange: size)

在视图中工作加载或刷新UIImageView的“reloadInputViews（）”；-）

**

编辑 **

嗨，如果需要，创建此扩展

创建文件扩展.Swift和添加此代码（在需要更改高度的位置添加导入基础）

供使用（继承UIView）

---

Swift 3.0版本（来自@YannickSteph）

---

如果您想保持纵横比，这里有一个扩展方法 Swift 3：

import UIKit

extension UIImage {

    func resize(maxWidthHeight : Double)-> UIImage? {

        let actualHeight = Double(size.height)
        let actualWidth = Double(size.width)
        var maxWidth = 0.0
        var maxHeight = 0.0

        if actualWidth > actualHeight {
            maxWidth = maxWidthHeight
            let per = (100.0 * maxWidthHeight / actualWidth)
            maxHeight = (actualHeight * per) / 100.0
        }else{
            maxHeight = maxWidthHeight
            let per = (100.0 * maxWidthHeight / actualHeight)
            maxWidth = (actualWidth * per) / 100.0
        }

        let hasAlpha = true
        let scale: CGFloat = 0.0

        UIGraphicsBeginImageContextWithOptions(CGSize(width: maxWidth, height: maxHeight), !hasAlpha, scale)
        self.draw(in: CGRect(origin: .zero, size: CGSize(width: maxWidth, height: maxHeight)))

        let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
        return scaledImage
    }

}

---

为什么不改为设置

UIImageView

的帧大小？除非您确实希望使用上下文绘制全新的

UIImage

。如果您的imageView已经声明并且具有宽度和高度限制，该怎么办？如何更改它？imageView.frame=CGRect（x:100，y:150，width:150，height:150）这对我不起作用，因为它与imageView对宽度和高度的自动布局约束冲突。要使建议在Swift 3或更高版本中起作用，请将第一行替换为：var imageView=UIImageView（frame:CGRect）（x:0，y:0，width:50，height:50））将高度和宽度放入

CGSize

对象中，并在调用该对象时将其传递给

imageResize

方法。

inheritsOfUIView.setHeight(height: 100)
button.setHeight(height: 100)
view.setHeight(height: 100)

extension UIImage {

    func imageResize (sizeChange:CGSize)-> UIImage{

        let hasAlpha = true
        let scale: CGFloat = 0.0 // Use scale factor of main screen

        UIGraphicsBeginImageContextWithOptions(sizeChange, !hasAlpha, scale)
        self.draw(in: CGRect(origin: CGPoint.zero, size: sizeChange))

        let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
        return scaledImage!
    }

}

import UIKit

extension UIImage {

    func resize(maxWidthHeight : Double)-> UIImage? {

        let actualHeight = Double(size.height)
        let actualWidth = Double(size.width)
        var maxWidth = 0.0
        var maxHeight = 0.0

        if actualWidth > actualHeight {
            maxWidth = maxWidthHeight
            let per = (100.0 * maxWidthHeight / actualWidth)
            maxHeight = (actualHeight * per) / 100.0
        }else{
            maxHeight = maxWidthHeight
            let per = (100.0 * maxWidthHeight / actualHeight)
            maxWidth = (actualWidth * per) / 100.0
        }

        let hasAlpha = true
        let scale: CGFloat = 0.0

        UIGraphicsBeginImageContextWithOptions(CGSize(width: maxWidth, height: maxHeight), !hasAlpha, scale)
        self.draw(in: CGRect(origin: .zero, size: CGSize(width: maxWidth, height: maxHeight)))

        let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
        return scaledImage
    }

}