objective-c - 编程 iOS : Document Preview, 更改完成按钮

Question

我正在使用 UIDocumentInteractionController 类来预览文档。是否可以将关闭预览的完成按钮更改为另一个按钮？例如，我想设置一个不同的标题:“关闭”而不是“完成”。

Answer 1

将完成按钮更改为完成按钮示例:

我读到您可以从 lastObject 获取导航项并更改左按钮或右按钮。

要更改完成按钮，您需要等待 Controller UIDocumentInteractionController View 完成显示。遗憾的是没有办法知道这一点，但是有:

• (void)documentInteractionControllerWillBeginPreview:(UIDocumentInteractionController *) Controller

这会告诉您它何时开始。

我所做的:添加一个计时器，当 Controller 准备就绪时，然后获取导航栏项目按钮并将其替换为新按钮。

1) 在.h中添加委托(delegate)和定时器

.. UIViewController <UIDocumentInteractionControllerDelegate>
@property (nonatomic, strong) NSTimer *timer;

2) 在.m

#import "UIView+BK.h"

- (void)documentInteractionControllerWillBeginPreview:(UIDocumentInteractionController *)controller{
        //Start timer
        _timer = [NSTimer scheduledTimerWithTimeInterval:.05
                                                  target:self
                                                selector:@selector(checkNavigationBar)
                                                userInfo:_timer
                                                 repeats:YES]; //YES TO CYCLE
    }

- (void) checkNavigationBar
    {
        //get the last view open (the UIDocumentInteractionController View)
        UIView *lastWindow = [[[[UIApplication sharedApplication] keyWindow ] subviews] lastObject];

        //Find the controller the view belongs too. 
        UIViewController *controller = [lastWindow findViewController];

        if (controller) {
            //find navigation bar using a category
            UINavigationBar *bar = [controller.view navigationBarFromView];

            //get the navigationItem
            UINavigationItem *item = bar.topItem;

            //get the done button
            UIBarButtonItem *doneButton = item.leftBarButtonItem ;

            //Creates the new button
            UIBarButtonItem *newDoneButton = [[UIBarButtonItem alloc ]
                                            initWithTitle:@"Finished"
                                            style:UIBarButtonItemStylePlain
                                            target:doneButton.target
                                            action:doneButton.action];

            //change done button
            item.leftBarButtonItem = newDoneButton;

            //Stop timer
            [_timer invalidate];
            _timer = nil;
        }
    }

3) 你需要这个类别

标题类别:

导入

@interface UIView (BK)

- (UIViewController *)findViewController;

- (UINavigationBar *)navigationBarFromView;
@end

实现类:

#import "UIView+BK.h"

@implementation UIView (BK)
- (UIViewController *)findViewController {
    Class vcc = [UIViewController class];    // Called here to avoid calling it iteratively unnecessarily.
    UIResponder *responder = self;
    while ((responder = [responder nextResponder])) if ([responder isKindOfClass: vcc]) return (UIViewController *)responder;
    return nil;
}

- (UINavigationBar *)navigationBarFromView {

    for (UIView *subview in self.subviews) {
        if ([subview isKindOfClass:[UINavigationBar  class]]) {
            return (UINavigationBar *)subview;
        }

        UIView *result = [subview navigationBarFromView];
        if (result) {
            return (UINavigationBar *)result;
        }

    }
    return nil;
}
@end