iOS UIContentViewMode各种效果 可解决相册照片的拉伸

1.系统的方法

typedef enum {    UIViewContentModeScaleToFill,    UIViewContentModeScaleAspectFit,      // contents scaled to fit with fixed aspect. remainder is transparent    UIViewContentModeScaleAspectFill,     // contents scaled to fill with fixed aspect. some portion of content may be clipped.    UIViewContentModeRedraw,              // redraw on bounds change (calls -setNeedsDisplay)    UIViewContentModeCenter,              // contents remain same size. positioned adjusted.    UIViewContentModeTop,    UIViewContentModeBottom,    UIViewContentModeLeft,    UIViewContentModeRight,    UIViewContentModeTopLeft,    UIViewContentModeTopRight,    UIViewContentModeBottomLeft,    UIViewContentModeBottomRight,} UIViewContentMode;

效果图如下