调整UITableView ImageView的大小

Question

如何在UITableViewCell中调整UIImageView的大小？我传入一个大图像（至少100x100px），所以图像本身不应该是问题（它应该缩小图像视图）

 cell.imageView.image = [UIImage imageNamed:@"unread.png"];


                CGSize itemSize = CGSizeMake(25, 25);
                UIGraphicsBeginImageContext(itemSize);
                CGRect imageRect = CGRectMake(0.0, 0.0, itemSize.width, itemSize.height);
                [cell.imageView.image drawInRect:imageRect];
                cell.imageView.image = UIGraphicsGetImageFromCurrentImageContext();
                UIGraphicsEndImageContext();

通常，UITableViewCell中的UIImageView的高度和宽度为43点（或86像素）。我想将它调整到20 x 20，但这没有做任何事情。我错过了什么吗？

Answer 1

您无法更改uitableviewcell的uiimageview框架。您可以从下面选择一个选项

1. 创建一个自定义单元格并根据您的要求放置一个uiimageview（这是最好的解决方案，我更喜欢这个）。

2. 在 cellForRowAtIndexPath中使用核心图形：

   CGSize itemSize = CGSizeMake(width, height);
   UIGraphicsBeginImageContext(itemSize);
   CGRect imageRect = CGRectMake(0.0, 0.0, itemSize.width, itemSize.height);
   [cell.imageView.image drawInRect:imageRect];
   cell.imageView.image = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();
   

Answer 2

我希望以下功能对您有用：

+(UIImage*)resizeImage:(UIImage *)image width:(int)width height:(int)height  {

CGFloat targetWidth = width;
CGFloat targetHeight = height;

CGImageRef imageRef = [image CGImage];
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);

if (bitmapInfo == kCGImageAlphaNone) {
    bitmapInfo = kCGImageAlphaNoneSkipLast;
}

CGContextRef bitmap;

if (image.imageOrientation == UIImageOrientationUp || image.imageOrientation == UIImageOrientationDown) {
    bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

} else {
    bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

}   


// In the right or left cases, we need to switch scaledWidth and scaledHeight,
// and also the thumbnail point
if (image.imageOrientation == UIImageOrientationLeft) {
    CGContextRotateCTM (bitmap, radians(90));
    CGContextTranslateCTM (bitmap, 0, -targetHeight);

} else if (image.imageOrientation == UIImageOrientationRight) {
    CGContextRotateCTM (bitmap, radians(-90));
    CGContextTranslateCTM (bitmap, -targetWidth, 0);

} else if (image.imageOrientation == UIImageOrientationUp) {
    // NOTHING
} else if (image.imageOrientation == UIImageOrientationDown) {
    CGContextTranslateCTM (bitmap, targetWidth, targetHeight);
    CGContextRotateCTM (bitmap, radians(-180.));
}

CGContextDrawImage(bitmap, CGRectMake(0, 0, targetWidth, targetHeight), imageRef);
CGImageRef ref = CGBitmapContextCreateImage(bitmap);
UIImage* newImage = [UIImage imageWithCGImage:ref];

CGContextRelease(bitmap);
CGImageRelease(ref);

return newImage; 
}