http://blog.cnbang.net/tech/1778/

 

问题

UINavigationController顶部的返回按钮在切换视图时有左右滑动的动画(效果见iMail),但在自定义了这个按钮后(通过设self.navigationItem.leftBarButtonItem自定义),切换视图时按钮没有了动画。

最初解决方法

在每个viewController的viewWillAppear和viewDisappear方法上手动让按钮左右动。由于每个视图出现/消失的方向都有左/右两种,在这里难以判断,需要各种变量辅助,实现十分恶心,中间需要新加view时逻辑还要重新修改,被折腾。

最终解决方法

继承UINavigationController,重写pushViewController和popViewController方法,在这两 个方法里面获取NavigationController里的view栈,因为push和pop总是操作最前面的View,所以可以从栈里知道哪两个 view是要做动画的。调用这些view相应的方法使他们让自己的按钮动。这些方法可以写在UIViewController的扩展里,不用修改每一个 viewController。

换言之,把下面的代码加入项目里,把项目里的UINavigationController换成下面的类,那些自定义的返回按钮就会自动做动画了。

代码

https://github.com/bang590/iOSPlayground/tree/master/NavigationButtonAnimate

01.//.h
02.#import <Foundation/Foundation.h>
03.@interface MainNavigationController : UINavigationController {
04.}
05.@end
06. 
07.//.m
08.#import "MainNavigationController.h"
09.@implementation UIViewController (UINavigationButtonAnimate)
10.- (void) viewAppearFromLeft
11.{
12.    [self.navigationItem.leftBarButtonItem.customView setTransform:CGAffineTransformMakeTranslation(-60, 0)];
13.    [UIView beginAnimations:@"viewAppearFromLeft" context:nil];
14.    [UIView setAnimationDuration:0.3];
15.    [self.navigationItem.leftBarButtonItem.customView setAlpha:1.0];
16.    [self.navigationItem.leftBarButtonItem.customView setTransform:CGAffineTransformMakeTranslation(0, 0)];
17.    [UIView commitAnimations];
18.}
19.- (void) viewAppearFromRight
20.{
21.    [self.navigationItem.leftBarButtonItem.customView setTransform:CGAffineTransformMakeTranslation(60, 0)];
22.    [UIView beginAnimations:@"viewAppearFromRight" context:nil];
23.    [UIView setAnimationDuration:0.3];
24.    [self.navigationItem.leftBarButtonItem.customView setAlpha:1.0];
25.    [self.navigationItem.leftBarButtonItem.customView setTransform:CGAffineTransformMakeTranslation(0, 0)];
26.    [UIView commitAnimations];
27.}
28.- (void) viewDisappearFromLeft
29.{
30.    [UIView beginAnimations:@"viewDisappearFromLeft" context:nil];
31.    [self.navigationItem.leftBarButtonItem.customView setTransform:CGAffineTransformMakeTranslation(60, 0)];
32.    [UIView setAnimationDuration:0.3];
33.    [self.navigationItem.leftBarButtonItem.customView setAlpha:0];
34.    [UIView commitAnimations];
35.}
36.- (void) viewDisappearFromRight
37.{
38.    [UIView beginAnimations:@"viewDisappearFromRight" context:nil];
39.    [self.navigationItem.leftBarButtonItem.customView setTransform:CGAffineTransformMakeTranslation(-60, 0)];
40.    [UIView setAnimationDuration:0.3];
41.    [self.navigationItem.leftBarButtonItem.customView setAlpha:0];
42.    [UIView commitAnimations];
43.}
44.@end
45. 
46.@implementation MainNavigationController
47.- (UIViewController *)popViewControllerAnimated:(BOOL)animated
48.{
49.    if (animated) {
50.        UIViewController *popController = [self.viewControllers lastObject];
51.        UIViewController *pushController = [self.viewControllers objectAtIndex:self.viewControllers.count - 2];
52.        [popController viewDisappearFromLeft];
53.        [pushController viewAppearFromLeft];
54.    }
55.    return [super popViewControllerAnimated:animated];
56.}
57.- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
58.{
59.    if (animated) {
60.        UIViewController *popController = [self.viewControllers lastObject];
61.        UIViewController *pushController = viewController;
62.        [popController viewDisappearFromRight];
63.        [pushController viewAppearFromRight];
64.    }
65.    [super pushViewController:viewController animated:animated];
66.}
67.@end