按钮内部布局

//布局按钮图片
- (CGRect)imageRectForContentRect:(CGRect)contentRect
{
    return CGRectMake(0, 0, contentRect.size.width, contentRect.size.height);
}

//布局按钮文字
- (CGRect)titleRectForContentRect:(CGRect)contentRect
{
    return CGRectMake(0, 30, 70, 30);
}

//布局按钮图片和文字
- (void)layoutSubviews
{
    [super layoutSubviews];

    CGFloat buttonW = self.frame.size.width;
    CGFloat buttonH = self.frame.size.height;

    CGFloat imageH = buttonW - 10;
    self.imageView.frame = CGRectMake(0, 0, buttonW, imageH);

    self.titleLabel.frame = CGRectMake(0, imageH, buttonW, buttonH - imageH);
}