即使 contentMode = UIViewContentModeScaleAspectFit，UIImageView 图像也会被拉伸(stretch)

Question

我对 UIImageView 显示图像的方式感到非常失望。

我有以下代码:

UIImageView *imgview = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 300, 100)];
imgview.image = [UIImage imageNamed:@"img.JPG"];
imgview.backgroundColor = [UIColor greenColor];
imgview.contentMode = UIViewContentModeScaleAspectFit;
[self.view addSubview:imgview];

我得到的是以下屏幕截图:

http://img26.imageshack.us/img26/3686/screenshot20130123at629.png

[图像被拉伸(stretch)到 UIImageView 的全宽，甚至没有全高]

原图:

http://img248.imageshack.us/img248/341/screenshot20130123at638.png

Answer 1

设置大小必须在设置 contentMode 之后发生

[imageView setContentMode: UIViewContentModeScaleAspectFit];
imageView.frame = CGRectMake(x, y, width, height);