Ios 调整大小后裁剪UIImage的底部

我有这张照片（原版尺寸）

我想调整图像的大小，将纵横比保持在600 x 600。在那之后，我只想裁剪这一帧的底部：

{0400600200}

，以获得图像的底部

通过保留纵横比调整大小效果很好，但我无法裁剪图像的底部。我使用以下代码根据纵横比调整大小：

CGFloat horizontalRatio = bounds.width / self.size.width;
CGFloat verticalRatio = bounds.height / self.size.height;
CGFloat ratio;

switch (contentMode) {
    case UIViewContentModeScaleAspectFill:
        ratio = MAX(horizontalRatio, verticalRatio);
        break;

    case UIViewContentModeScaleAspectFit:
        ratio = MIN(horizontalRatio, verticalRatio);
        break;

    default:
        [NSException raise:NSInvalidArgumentException format:@"Unsupported content mode: %d", contentMode];
}

CGSize newSize = CGSizeMake(self.size.width * ratio, self.size.height * ratio);
UIImage *resizedImg = [self resizedImage:newSize interpolationQuality:quality];
if (UIViewContentModeScaleAspectFill == contentMode && (newSize.height > bounds.height || newSize.width > bounds.width)) {
    CGRect newRect = CGRectMake((newSize.width - bounds.width) / 2, (newSize.height - bounds.height) / 2, bounds.width, bounds.height);
    CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], bounds);
    UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);
    return croppedImage;
}
return resizedImg;

这个代码用来裁剪底部

CGRect rect = CGRectMake(0, 400, 600, 200);
CGImageRef imageRef = CGImageCreateWithImageInRect([newImage CGImage], rect);
UIImage *cropped = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);

这就是我得到的结果（我应该得到相同的图像，我想使该裁剪模糊底部裁剪区域以显示一些文本）：

帮助我解决了这个问题。我用错误的值初始化图像的帧。

非常简单

- (UIImage *)cropImage:(UIImage *)oldImage {

CGSize imageSize = oldImage.size;

UIGraphicsBeginImageContextWithOptions( CGSizeMake( imageSize.width,
                                                    imageSize.height - 200),
                                        NO,
                                        0.);
[oldImage drawAtPoint:CGPointMake( 0, -100)
            blendMode:kCGBlendModeCopy
                alpha:1.];

UIImage *croppedImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return croppedImage;
}

这就是救我的原因

func cropImage(_ inputImage: UIImage, toRect cropRect: CGRect, viewWidth: CGFloat, viewHeight: CGFloat) -> UIImage? 
{    
let imageViewScale = max(inputImage.size.width / viewWidth,
                         inputImage.size.height / viewHeight)

// Scale cropRect to handle images larger than shown-on-screen size
let cropZone = CGRect(x:cropRect.origin.x * imageViewScale,
                      y:cropRect.origin.y * imageViewScale,
                      width:cropRect.size.width * imageViewScale,
                      height:cropRect.size.height * imageViewScale)

// Perform cropping in Core Graphics
guard let cutImageRef: CGImage = inputImage.cgImage?.cropping(to:cropZone)
else {
    return nil
}

// Return image to UIImage
let croppedImage: UIImage = UIImage(cgImage: cutImageRef)
return croppedImage
}

---

您能否具体说明帧的哪一部分在代码中有错误的值？谢谢。底部框架的图像大小相同，但位置不同。如果你想获得相同的结果，请检查这个

UIImage

category:Hi@devjme我使用了相同的函数，但它给了我一个横向图像而不是纵向图像。函数调用：

UIImage*cropedimage=[self-cropImage:image-toRect:CGRectMake（self.capturedImageView.frame.size.width/4,0，self.capturedImageView.frame.size.width/2，self.capturedImageView.frame.size.width）viewWidth:self.capturedImageView.frame.size.height]任何帮助都将不胜感激。