//只需如下设置imageView

　[picImg setContentScaleFactor:[[UIScreenmainScreen] scale]];

    picImg.contentMode =  UIViewContentModeScaleAspectFill;

    picImg.autoresizingMask = UIViewAutoresizingFlexibleWidth;//根据你的需求

    picImg.clipsToBounds  = YES;//切掉多余部分

iOS UIImageView 显示不规则图片只显示图片一部分保证图片不被压缩