开发笔记-图片拉伸保持不变形

1.
// 1.创建个图片对象
    UIImage *image = [UIImage imageNamed:@"buttongreen"];

    // 2.根据图片创建一个可以拉伸的图片
    image = [image resizableImageWithCapInsets:UIEdgeInsetsMake(10, 10, 10, 10)];

    [self.btn setBackgroundImage:image forState:UIControlStateNormal];

2.

    // 1.创建个图片对象
    UIImage *image = [UIImage imageNamed:@"chat"];

    // 2.获得可拉伸的区域
    CGFloat imageW = image.size.width;
    CGFloat imageH = image.size.height;
    // 3.根据图片创建一个可以拉伸的图片
    image = [image resizableImageWithCapInsets:UIEdgeInsetsMake(imageH * 0.5, imageW * 0.5, imageH * 0.5, imageW * 0.5) resizingMode:UIImageResizingModeTile];
    [self.btn setBackgroundImage:image forState:UIControlStateNormal];