iphone - 使用 UIAppearance 时 UIBarButtonItem 的奇怪行为

Question

我正在使用 UIAppearance 自定义导航栏、选项卡栏和 uibarbuttonitem 等元素。除了 UIBarButtonItem 元素的非常奇怪的行为外，它工作得很好。在导航 Controller 层次结构的顶层，一切看起来都不错，但如果我按下下一个 View Controller ，UIBarButtonItem 元素会稍微向下移动一点，但与此同时，后退按钮会保持在正确的位置。我附上了两张图片来说明我的问题。

1) 导航 Controller 层次结构中的第一个 View Controller

2) 导航 Controller 层次结构中的第二个 View Controller

编辑:代码

    //Change navigation bar appearance
    [[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@"GPNavigationBarBackground.png"] forBarMetrics:UIBarMetricsDefault];
    [[UINavigationBar appearance] setShadowImage:[[UIImage alloc] init]];
    [[UINavigationBar appearance] setShadowImage:[UIImage imageNamed:@"GPNavigationBarShadow.png"]];

    [[UINavigationBar appearance] setTitleTextAttributes:
     [NSDictionary dictionaryWithObjectsAndKeys:
      [UIColor whiteColor], UITextAttributeTextColor,
      [UIFont boldSystemFontOfSize:17], UITextAttributeFont,nil]];
    [[UINavigationBar appearance] setTitleVerticalPositionAdjustment:2.f forBarMetrics:UIBarMetricsDefault];

    UIImage *buttonBackground = [[UIImage imageNamed:@"GPNavigationBarButton.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 10, 0, 10)];
    UIImage *buttonPressedBackground = [[UIImage imageNamed:@"GPNavigationBarButtonPressed.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 10, 0, 10)];

    UIImage *backButtonBackground = [[UIImage imageNamed:@"GPNavigationBarBackButton.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 15, 0, 10)];
    UIImage *backButtonPressedBackground = [[UIImage imageNamed:@"GPNavigationBarBackButtonPressed.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 15, 0, 10)];

    [[UIBarButtonItem appearance] setBackgroundImage:buttonBackground forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
    [[UIBarButtonItem appearance] setBackgroundImage:buttonPressedBackground forState:UIControlStateHighlighted barMetrics:UIBarMetricsDefault];

    [[UIBarButtonItem appearance] setBackButtonBackgroundImage:backButtonBackground forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
    [[UIBarButtonItem appearance] setBackButtonBackgroundImage:backButtonPressedBackground forState:UIControlStateHighlighted barMetrics:UIBarMetricsDefault];

    [[UIBarButtonItem appearance] setBackButtonBackgroundVerticalPositionAdjustment:1.f forBarMetrics:UIBarMetricsDefault];
    [[UIBarButtonItem appearance] setBackgroundVerticalPositionAdjustment:1.f forBarMetrics:UIBarMetricsDefault];
    [[UIBarButtonItem appearance] setTitlePositionAdjustment:UIOffsetMake(0, 1.f) forBarMetrics:UIBarMetricsDefault];

Answer 1

好吧，经过我对那个问题的思索，我终于解决了它。上面的代码是完全正确的。唯一的问题是 UIBarButtonItem 的背景图像的高度。 UIAppearance 代理允许您设置所有图形，但不允许您更改 UIBarButtonItem 的高度。

So, when customizing UIBarButtonItem, always remember that a UIBarButtonItem can't be higher than 30pt. That means that custom artwork shouldn't exceed this size.

你可以设置高于30pt的背景图片，但你会遇到与上述相同的问题。