ios - UIButton - 只能在一个方向上拉伸(stretch)背景图像？

Question

我有一个 UIButton 对象，我在其中使用可伸缩图像作为其背景，因此我始终可以拥有灵活的按钮大小。

问题是我想要一个固定的图像高度(比如 32px)，但想要一个更高的可触摸区域(Apple UI Guidelines 总是说至少 44px 高)。

如果我在 x 轴上有一个可拉伸(stretch)的图像，不幸的是它也在 y 轴上拉伸(stretch)。我想告诉图像不要在 y 方向拉伸(stretch)。这可能吗？

[编辑] 是的。回答我自己的问题:

Answer 1

所以，为了帮助别人，我可以回答我自己的问题:

@interface StretchableXButton : UIButton
{
    CGFloat imageHeight;
}
@property CGFloat imageHeight;  // we need this later when we override an instance method

+ (id)buttonWithFrame:(CGRect)frame;

@end

现在是实现:

@implementation StretchableXButton
@synthesize imageHeight; 

+ (id)buttonWithFrame:(CGRect)frame
{
    StretchableXButton *button = [super buttonWithType:UIButtonTypeCustom];

    UIImage *normalImage = [UIImage imageNamed: @"ButtonBGNormal.png" ];
    UIImage *highlightedImage = [UIImage imageNamed:@"ButtonBGHighlighted.png" ];

    button.frame = frame;
    button.imageHeight = normalImage.size.height;  // we need him later in the method below

    // make the images stretchable
    normalImage = [normalImage stretchableImageWithLeftCapWidth:normalImage.size.width/2 topCapHeight:normalImage.size.height/2];
    highlightedImage = [highlightedImage stretchableImageWithLeftCapWidth:normalImage.size.width/2 topCapHeight:normalImage.size.height/2];

    button.backgroundColor = [UIColor clearColor];

    // SET OTHER BUTTON PROPERTIES HERE (textLabel, fonts, etc.)

    [button setBackgroundImage:normalImage forState:UIControlStateNormal];
    [button setBackgroundImage:highlightedImage forState:UIControlStateHighlighted];

    return  button;
}

// THIS IS THE TRICK.  We make the height of the background rect match the image.
-(CGRect)backgroundRectForBounds:(CGRect)bounds
{
    CGRect bgRect = bounds;
    bgRect.origin.y = (bounds.size.height - imageHeight)/2.0f;
    bgRect.size.height = imageHeight;

    return bgRect;
}


@end