ios图片拉伸两种方法

 UIImage *image = [UIImage imageNamed:@"qq"];

 // 左端盖宽度
    NSInteger leftCapWidth = image.size.width * 0.5f;
    // 顶端盖高度
    NSInteger topCapHeight = image.size.height * 0.5f;
    // 重新赋值
    image = [image stretchableImageWithLeftCapWidth:leftCapWidth topCapHeight:topCapHeight];

    CGFloat top = 25; // 顶端盖高度
    CGFloat bottom = 25 ; // 底端盖高度
    CGFloat left = 10; // 左端盖宽度
    CGFloat right = 10; // 右端盖宽度
    UIEdgeInsets insets = UIEdgeInsetsMake(top, left, bottom, right);
    // 指定为拉伸模式，伸缩后重新赋值
    image = [image resizableImageWithCapInsets:insets resizingMode:UIImageResizingModeStretch];

 [button setBackgroundImage:image forState:UIControlStateNormal];