修复容易，一旦我找到文档!

 imageView.contentMode = .scaleAspectFit

您可以尝试使imageView大小与图像匹配。下面的代码没有经过测试。

CGSize kMaxImageViewSize = {.width = 100, .height = 100};
CGSize imageSize = image.size;
CGFloat aspectRatio = imageSize.width / imageSize.height;
CGRect frame = imageView.frame;
if (kMaxImageViewSize.width / aspectRatio <= kMaxImageViewSize.height) 
{
    frame.size.width = kMaxImageViewSize.width;
    frame.size.height = frame.size.width / aspectRatio;
} 
else 
{
    frame.size.height = kMaxImageViewSize.height;
    frame.size.width = frame.size.height * aspectRatio;
}
imageView.frame = frame;

imageView.contentMode = UIViewContentModeScaleAspectFill;
imageView.clipsToBounds = YES;

UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://farm4.static.flickr.com/3092/2915896504_a88b69c9de.jpg"]]];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image]; 


//set contentMode to scale aspect to fit
imageView.contentMode = UIViewContentModeScaleAspectFit;

//change width of frame
//CGRect frame = imageView.frame;
//frame.size.width = 100;
//imageView.frame = frame;

//original lines that deal with frame commented out, yo.
imageView.frame = CGRectMake(10, 20, 60, 60);

...

//Add image view
[myView addSubview:imageView]; 

上面的原始代码在iOS 4.2中运行得很好。

我发现创建一个CGRect并指定所有的顶部，左侧，宽度和高度值是在我的情况下调整位置的最简单的方法，这是在表格单元格中使用UIImageView。(仍然需要添加代码来释放对象)

UIImageView + Scale.h:

#import <Foundation/Foundation.h>

@interface UIImageView (Scale)

-(void) scaleAspectFit:(CGFloat) scaleFactor;

@end

UIImageView + Scale.m:

#import "UIImageView+Scale.h"

@implementation UIImageView (Scale)


-(void) scaleAspectFit:(CGFloat) scaleFactor{

    self.contentScaleFactor = scaleFactor;
    self.transform = CGAffineTransformMakeScale(scaleFactor, scaleFactor);

    CGRect newRect = self.frame;
    newRect.origin.x = 0;
    newRect.origin.y = 0;
    self.frame = newRect;
}

@end

如果这里提出的解决方案对您不起作用，并且您的图像资产实际上是PDF，请注意XCode实际上将PDF与图像文件区别对待。特别是，它似乎不能适当地缩放以填充PDF:它最终是平铺的。这让我抓狂，直到我发现问题出在PDF格式上。将其转换为JPG格式，然后就可以开始了。