UIImageView *imageView = [[UIImageView alloc] init];
// 防止圖片變形
imageView.contentMode = UIViewContentModeScaleAspectFill;
imageView.clipsToBounds=YES;//? 是否剪切掉超出 UIImageView 范圍的圖片
[imageView setContentScaleFactor:[[UIScreen mainScreen] scale]];
_imageView = imageView;
[self addSubview:imageView];
防止圖片壓縮的處理