ios 图片不被扭曲

UIImageView＊ imageView ＝ [[UIImageView alloc] init];

imageView.contentMode=UIViewContentModeScaleAspectFill;

imageView.clipsToBounds=YES;//  是否剪切掉超出 UIImageView 范围的图片

[imageView setContentScaleFactor:[[UIScreen mainScreen] scale]];