Xcode6.2，OSX 10.10.3beta，为什么在iOS7.1模拟器中可以正常运行，在iOS8版本以上模拟器中无效。。。

 - (void)titleButtonClick:(XXTitleButton *)titleButton {
    UIImage *down = [UIImage imageWithName:@"navigationbar_arrow_down"];
    UIImage *up = [UIImage imageWithName:@"navigationbar_arrow_up"];
    if (titleButton.currentImage == down) {
        [titleButton setImage:up forState:UIControlStateNormal];
        [self.view addSubview:self.titleMenu];
    }else {
        [titleButton setImage:down forState:UIControlStateNormal];
        [self.titleMenu removeFromSuperview];
    }

}