Tableview cell shaking when image size is too large

Question

我必须在固定大小的区域（例如100 * 100 px）中显示图像，但实际图像大小太大（例如400 * 450），问题是当我在100 * 100 px imageview中设置大图像时，滚动会产生单元抖动

Answer 1

I used this single line of code to create a new UIImage which is scaled. Set the scale and orientation params to achieve what you want. The first line of code just grabs the image.

// grab the original image
UIImage *originalImage = [UIImage imageNamed:@"myImage.png"];
// scaling set to 2.0 makes the image 1/2 the size. 
UIImage *scaledImage = 
            [UIImage imageWithCGImage:[originalImage CGImage] 
                          scale:(originalImage.scale * 2.0)
                             orientation:(originalImage.imageOrientation)];

The simplest way is to set the frame of your UIImageView and set the contentMode to one of the resizing options.

Or you can use this utility method, if you actually need to resize an image:

+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
    //UIGraphicsBeginImageContext(newSize);
    // In next line, pass 0.0 to use the current device's pixel scaling factor (and thus account for Retina resolution).
    // Pass 1.0 to force exact pixel size.
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    
    UIGraphicsEndImageContext();
    return newImage;
}