UIImagePickerController 导航栏项的更改案例

问题描述

免责声明:我意识到这可能不会得到 Apple 的批准，并且我意识到遍历视图层次结构在编程上是不安全的.我正出于自己的好奇心想弄清楚:)

Disclaimer: I realize this may not be approved by Apple, and I realize traversing the view hierarchy is programmatically unsafe. I'm trying to figure it out for my own curiosity :)

我想更改 UIImagePickerController 导航栏项的大小写.

I'd like to change the case of a UIImagePickerController's navigation bar items.

这适用于标题文本:

viewController.navigationItem.title = [viewController.navigationItem.title uppercaseString];

但这对取消按钮不起作用(显然它不是取消按钮的正确位置，但我在视图层次结构中找不到它).

But this doesn't work for the cancel button (clearly it's not the right location for the cancel button, but I can't find it in the view hierarchy).

如何更改取消按钮?

[viewController.navigationItem.rightBarButtonItems enumerateObjectsUsingBlock:^(UIBarButtonItem* btn, NSUInteger idx, BOOL *stop) {
    btn.title  = [btn.title lowercaseString];
}];

推荐答案

我不知道如何访问现有的取消按钮，但您可以通过以下方式替换它:

I don't know how to access the existing cancel button, but you can replace it doing something like this:

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    // add done button to right side of nav bar
    UIBarButtonItem *cancelButton = [[UIBarButtonItem alloc] initWithTitle:@"cancel"
                                                                     style:UIBarButtonItemStylePlain
                                                                    target:self
                                                                    action:@selector(done:)];

    UINavigationBar *bar = navigationController.navigationBar;
    UINavigationItem *topItem;

    topItem = bar.topItem;
    topItem.rightBarButtonItem = cancelButton;
}

这会做你想做的，我想:

This will do what you want, I think:

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    for (UIView *view in navigationController.navigationBar.subviews)
    {
        if ([view isKindOfClass:[UIButton class]])
        {
            UIButton *btn = (UIButton *)view;
            [btn setTitle:[btn.titleLabel.text lowercaseString] forState:UIControlStateNormal];
        }
    }
}

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