UIViewContentMode

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;

UIViewContentModeScaleToFill

UIViewContentModeScaleToFill 充滿frame會變形

UIViewContentModeScaleAspectFit 長邊為主 短邊留縫隙

UIViewContentModeScaleAspectFit 長邊為主 短邊留縫隙

UIViewContentModeScaleAspectFill 短邊為主 長邊截取

UIViewContentModeScaleAspectFill 短邊為主 長邊截取

UIViewContentModeCenter 標尺圖片原始尺寸 frame太小會超出

UIViewContentModeCenter 標尺圖片原始尺寸 frame太小會超出

UIViewContentModeTop 標尺圖片原始尺寸 frame太小會超出

UIViewContentModeTop 標尺圖片原始尺寸 frame太小會超出