2014年4月份第一次接触IOS端开发,为某银行开发一款金融app。
在开发的最后阶段,加入了需要从任意一个页面直接返回主页的功能。
悲催的是,当时没有使用UINavigationController进行导航管理,而是使用了IOS中的模态跳转方式(presentViewController/dismissViewControllerAnimated).
因此需要找的一种方法进行,实现如下方式的导航跳转:
面对上面的需求,最简单的方式是将所有控制器都改成UINavigationController,并且利用pushViewController / popToViewController/ popToRootViewControllerAnimated 等方法进行完美解题。但是当时项目的页面将近100个,分成三大模块,需要大规模修改设计页面以及调整大量代码,这并不是一个现实的解决方案,不到万不得已,不能采取如此低劣手段!
我们需要一个满足如下条件的解决方案:
1) 对于已经在InterfaceBuilder中完成的页面,不做任何修改 2) 尽量少的修改代码,因为很多代码已经经过测试中心测试过,如果修改,需要全部重新测试,时间来不及。
当时通过两天的研究,深入的了解了IOS中的跳转流程和生命周期后,找到了一个相对完美的解决方案,能够满足上面提到的要求。通过一个Demo,来和大家一起分享。
1) 为了减少代码的修改,增加一个基类。
@interface BaseViewController : UIViewController //防止controller循环引用,使用weak引用方式 @property(nonatomic,weak) BaseViewController* parentController; //为了能够了解某个页面控制器生命周期相关信息,给该控制器取个名字 @property(nonatomic,copy) NSString* ctrlName; //关键的函数,进行页面c-->跳转到主页 -(void) doDismiss; @end
2) 为了更好的了解IOS中ViewController的生命周期,我们在基类中输出相关信息来了解生命周期相关信息。
@implementation BaseViewController -(id) init { self.ctrlName = @""; self.parentController = nil; return [super init]; } - (void)viewDidLoad { NSLog(@"%@ invoke viewDidLoad",self.ctrlName); [super viewDidLoad]; // Do any additional setup after loading the view. } -(void)viewWillAppear:(BOOL)animated { NSLog(@"%@ invoke viewWillAppear",self.ctrlName); [super viewWillAppear:animated]; } -(void)viewDidAppear:(BOOL)animated { NSLog(@"%@ invoke viewDidAppear",self.ctrlName); [super viewDidAppear:animated]; } -(void) viewWillDisappear:(BOOL)animated { NSLog(@"%@ invoke viewWillDisappear",self.ctrlName); [super viewWillDisappear:animated]; } -(void) viewDidDisappear:(BOOL)animated { NSLog(@"%@ invoke viewDidDisappear",self.ctrlName); [super viewDidDisappear:animated]; } - (void)didReceiveMemoryWarning { NSLog(@"%@ invoke didReceiveMemoryWarning",self.ctrlName); [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } -(void)dealloc { NSLog(@"%@ .......dealloc.......",self.ctrlName); }
3) 关键的递归函数,核心是理解dismissViewControllerAnimated:completion函数中completion回调的时机点,这个是解题的钥匙。
-(void)doDismiss { NSLog(@"%@ dismiss begin",self.ctrlName); if([self.parentController isKindOfClass:[ViewController class]]) { [self dismissViewControllerAnimated:YES completion: ^(void) { NSLog(@"%@ dismiss end",self.ctrlName); if(self.parentController) { [self.parentController doDismiss]; } }]; } else { [self dismissViewControllerAnimated:NO completion: ^(void) { NSLog(@"%@ dismiss end",self.ctrlName); if(self.parentController) { [self.parentController doDismiss]; } }]; } }
4) Demo页面结构如下图: MainViewController-->SecondViewController-->Child1ViewController,然后直接跳回到MainViewController. 5) 所有的ViewController都继承自我们自定义的BaseViewController,具有关键的doDismiss递归方法!
6) 看一下从MainViewController-->SecondViewController-->Child1ViewController-->MainViewController生命周期的相关信息:
a、启动程序,进入MainViewController:
2017-02-11 17:25:16.964 navTest[933:17086] mainViewCtrl invoke viewDidLoad
2017-02-11 17:25:16.966 navTest[933:17086] mainViewCtrl invoke viewWillAppear
2017-02-11 17:25:16.975 navTest[933:17086] mainViewCtrl invoke viewDidAppear
b、从MainViewController→SecondViewController:
2017-02-11 17:28:29.717 navTest[933:17086] SecondViewController invoke viewDidLoad [先newController调用viewDidLoad]
2017-02-11 17:28:29.721 navTest[933:17086] mainViewCtrl invoke viewWillDisappear [然后oldController调用viewWillDisappear]
2017-02-11 17:28:29.722 navTest[933:17086] SecondViewController invoke viewWillAppear [然后newController调用viewWillAppear]
2017-02-11 17:28:30.229 navTest[933:17086] SecondViewController invoke viewDidAppear [然后newController调用viewDidAppear ]
2017-02-11 17:28:30.229 navTest[933:17086] mainViewCtrl invoke viewDidDisappear [然后oldController调用viewDidDisappear ]
2017-02-11 17:28:30.230 navTest[933:17086] mainViewCtrl present end
[最后oldController调用presentViewController完成回调被调用]
下面是presentViewController完成回调信息的输出代码,用来了解completion是在哪个阶段被调用的,很重要的信息哦!!!
- (IBAction)ClickToEnterSecondController:(id)sender { SecondViewController* ctrl = [self.storyboard instantiateViewControllerWithIdentifier:@"second"]; ctrl.parentController = self; ctrl.ctrlName = @"SecondViewController"; [self presentViewController:ctrl animated:YES completion:^(void) { NSLog(@"%@ present end",self.ctrlName); }]; }
c、从Child1ViewController直接返回到MainViewController的流程(跳过SecondViewController)
- (IBAction)returnMainViewController:(id)sender { NSLog(@"**********************doDismiss*********************"); [self doDismiss]; }
d、2017-02-11 17:30:30.634 navTest[933:17086] **doDismiss* [要开始调用doDismiss函数了,表示点击了返回按钮]
2017-02-11 17:30:30.635 navTest[933:17086] Child1ViewController dismiss begin [输出dismiss begin,表示调用了Child1ViewController的doDismiss递归函数]
2017-02-11 17:30:30.637 navTest[933:17086] Child1ViewController invoke viewWillDisappear [oldController viewWillDisappear]
2017-02-11 17:30:30.638 navTest[933:17086] SecondViewController invoke viewWillAppear [newController viewWillAppear]
2017-02-11 17:30:30.641 navTest[933:17086] SecondViewController invoke viewDidAppear [newController viewDidAppear]
2017-02-11 17:30:30.641 navTest[933:17086] Child1ViewController invoke viewDidDisappear [oldController viewDidDisappear ]
2017-02-11 17:30:30.641 navTest[933:17086] Child1ViewController dismiss end [关键时刻哦,oldController self dismissViewControllerAnimated: completion: 中的completion 回调被触发了,它是在 oldController viewDidDisappear后被触发的哦]
2017-02-11 17:30:30.641 navTest[933:17086] SecondViewController dismiss begin [这时候,从ChildViewController回弹到SecondViewController的流程完成了,接下来递归调用,要完成从SecondViewController回弹到MainViewController的过程,重复上面的流程而已]
2017-02-11 17:30:30.642 navTest[933:17086] Child1ViewController …….dealloc……. [Child1ViewController已经完全消失了,因此内存被析构了,这样确保内存不会泄露哦]
2017-02-11 17:30:30.643 navTest[933:17086] SecondViewController invoke viewWillDisappear
2017-02-11 17:30:30.644 navTest[933:17086] mainViewCtrl invoke viewWillAppear
2017-02-11 17:30:31.156 navTest[933:17086] mainViewCtrl invoke viewDidAppear
2017-02-11 17:30:31.156 navTest[933:17086] SecondViewController invoke viewDidDisappear
2017-02-11 17:30:31.156 navTest[933:17086] SecondViewController dismiss end
2017-02-11 17:30:31.157 navTest[933:17086] mainViewCtrl dismiss begin
2017-02-11 17:30:31.157 navTest[933:17086] SecondViewController …….dealloc……. [SecondViewController 内存也很完美的被析构掉,目前仅剩下MainViewController还活着]
show一下某银行APP以前模拟器中的效果截图,IOS开发还是非常令人非常愉悦的感觉!
×××:
IOS UIViewController 导航及生命周期Demo
免责声明:本站发布的内容(图片、视频和文字)以原创、转载和分享为主,文章观点不代表本网站立场,如果涉及侵权请联系站长邮箱:is@yisu.com进行举报,并提供相关证据,一经查实,将立刻删除涉嫌侵权内容。