前言: 淺顯易讀, 看完就能明白的小技巧, 兩三分鐘足夠了, 非常實用, 點到為止.

把一個 64 x 64 的圖片 賦值給 size = 200 x 200的ImageView

    UIImageView *imageView = [UIImageView new];
  imageView.backgroundColor = [UIColor cyanColor];
  imageView.frame = CGRectMake(0, 0, 200, 200);
  UIImage *image = [UIImage imageNamed:@"rect"];
  imageView.image = image;
  imageView.center = CGPointMake(self.view.frame.size.width / 2, 200);
  [self.view addSubview:imageView];

很明顯模糊的非常嚴重, 特別的圓角邊

在iOS5 之後 系統提供一個API: 對邊緣部分不進行拉伸處理

  image = [image resizableImageWithCapInsets:UIEdgeInsetsMake(25, 25, 25, 25)];

iOS6 提供的API

- (UIImage *)resizableImageWithCapInsets:(UIEdgeInsets)capInsets resizingMode:(UIImageResizingMode)resizingMode NS_AVAILABLE_IOS(6_0); // the interior is resized according to the resizingMode

處理方式多了個參數可選類型

typedef NS_ENUM(NSInteger, UIImageResizingMode) {
  UIImageResizingModeTile, //  tile瓷磚的意思: 一塊一塊把牆面貼滿
  UIImageResizingModeStretch, // 單純拉伸
};