ios - UINavigationController "pushViewController:animated"的完成处理程序？

Question

我打算使用 UINavigationController 创建一个应用程序来呈现下一个 View Controller 。在 iOS5 中，有一种呈现 UIViewControllers 的新方法:

presentViewController:animated:completion:

现在我问我为什么 UINavigationController 没有完成处理程序？只有

pushViewController:animated:

是否可以创建我自己的完成处理程序，如新的 presentViewController:animated:completion: ？

Answer 1

参见 par's answer获取另一个更新的解决方案

UINavigationController 动画与 CoreAnimation 一起运行，因此将代码封装在 CATransaction 中并因此设置一个完成 block 是有意义的。

swift :

对于swift，我建议创建一个这样的扩展

extension UINavigationController {

  public func pushViewController(viewController: UIViewController,
                                 animated: Bool,
                                 completion: @escaping (() -> Void)?) {
    CATransaction.begin()
    CATransaction.setCompletionBlock(completion)
    pushViewController(viewController, animated: animated)
    CATransaction.commit()
  }

}

用法:

navigationController?.pushViewController(vc, animated: true) {
  // Animation done
}

objective-C

标题:

#import <UIKit/UIKit.h>

@interface UINavigationController (CompletionHandler)

- (void)completionhandler_pushViewController:(UIViewController *)viewController
                                    animated:(BOOL)animated
                                  completion:(void (^)(void))completion;

@end

实现:

#import "UINavigationController+CompletionHandler.h"
#import <QuartzCore/QuartzCore.h>

@implementation UINavigationController (CompletionHandler)

- (void)completionhandler_pushViewController:(UIViewController *)viewController 
                                    animated:(BOOL)animated 
                                  completion:(void (^)(void))completion 
{
    [CATransaction begin];
    [CATransaction setCompletionBlock:completion];
    [self pushViewController:viewController animated:animated];
    [CATransaction commit];
}

@end