ios圖片拉伸

#pragma mark iOS5之前的拉伸方式
#pragma mark 返回一張已經拉伸好的圖片
- (UIImage *)stretchiOS5before:(NSString *)icon {
    UIImage *image = [UIImage imageNamed:icon];
    CGFloat normalLeftCap = image.size.width * 0.5f;
    CGFloat normalTopCap = image.size.height * 0.5f;
    return [image stretchableImageWithLeftCapWidth:normalLeftCap topCapHeight:normalTopCap];
}

#pragma mark iOS5的拉伸方式
- (UIImage *) stretchiOS5:(NSString *)icon {
    UIImage *image = [UIImage imageNamed:icon];
    CGFloat normalLeftCap = image.size.width * 0.5f;
    CGFloat normalTopCap = image.size.height * 0.5f;
    // 13 * 34
    // 指定不需要拉伸的區域
    UIEdgeInsets insets = UIEdgeInsetsMake(normalTopCap, normalLeftCap, normalTopCap - 1, normalLeftCap - 1);
    return [image resizableImageWithCapInsets:insets];
}

#pragma mark iOS6的拉伸方式
- (UIImage *) stretchiOS6:(NSString *)icon {
    UIImage *image = [UIImage imageNamed:icon];
    CGFloat normalLeftCap = image.size.width * 0.5f;
    CGFloat normalTopCap = image.size.height * 0.5f;
    // 13 * 34
    // 指定不需要拉伸的區域
    UIEdgeInsets insets = UIEdgeInsetsMake(normalTopCap, normalLeftCap, normalTopCap - 1, normalLeftCap - 1);
    
    // ios6.0的拉伸方式只不過比iOS5.0多了一個拉伸模式參數
    return [image resizableImageWithCapInsets:insets resizingMode:UIImageResizingModeTile];
}