关于UIAlertView键盘弹起的问题

这里记录一下我在开发中遇到的一个奇葩的问题，经过百度后我发现这个问题确实存在，也有不少人遇到过，今天就把它写出来。其实我们单纯的使用UIAlertView是没什么问题的，但是当UI中有输入框时，当输入完成后，我们点击按钮弹出UIAlertView的时候，在点击UIAlertView上面的按钮跳转到下一个页面的时候，那么问题就来了，在后一个页面会弹出键盘。这个问题刚开始出现的时候，莫名奇妙，也找了好久，因为在模拟器上是不容易察觉的，在真机上就非常明显了。

• 下面我们模拟一下这个现象，在此来给大家加深印象，避免跟我一样遇到这个问题而纠结了。直接上代码。

• #import "ViewController.h"
  #import "ViewControllerOne.h"
  
  @interface ViewController ()<UIAlertViewDelegate>
  
  @end
  
  @implementation ViewController
  
  - (void)viewDidLoad {
      [super viewDidLoad];
      // Do any additional setup after loading the view, typically from a nib.
      UIButton *button = [UIButton buttonWithType:UIButtonTypeContactAdd];
      button.center = self.view.center;
      [self.view addSubview:button];
      [button addTarget:self action:@selector(click) forControlEvents:UIControlEventTouchUpInside];
      UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(50, 100, 100, 30)];
      textField.backgroundColor = [UIColor redColor];
      [self.view addSubview:textField];
      [self obserKeyboard];
  }
  
  #pragma mark - 键盘的监控
  - (void)obserKeyboard {
      [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
      [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardShow:) name:UIKeyboardDidShowNotification object:nil];
  
      [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
  
      [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardHide:) name:UIKeyboardDidHideNotification object:nil];
  }
  
  - (void)click {
      UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"测试UIAlertView" message:@"弊端" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"确定",@"好玩么", nil];
      [alertView show];
  }
  #pragma mark 键盘动作
  - (void)keyboardWillShow:(NSNotification *)notif {
      NSLog(@"键盘将要弹出-keyboardWillShow");
  }
  - (void)keyboardShow:(NSNotification *)notif {
      NSLog(@"键盘已经弹出-keyboardShow");
  }
  - (void)keyboardWillHide:(NSNotification *)notif {
      NSLog(@"键盘将要隐藏-keyboardWillHide");
  }
  - (void)keyboardHide:(NSNotification *)notif {
      NSLog(@"键盘已经隐藏-keyboardWillHide");
  
  }
  - (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
      if (buttonIndex == 1) {
          ViewControllerOne *ctl = [[ViewControllerOne alloc] init];
          [self.navigationController pushViewController:ctl animated:YES];
      }
  }

  简单说一下，就是在一个界面上有一个UITextField和一个按钮，按钮的点击事件就是弹出UIAlertView。下面说一下模拟现象的步骤。

1. 首先在UITextField输入一下文字
2. 输入完成后我们点击按钮，弹出UIAlertView这个时候我们监听到的键盘事件在控制台打印如下
3. 当我们点击UIAlertView的确定按钮的时候，push到ViewControllerOne。其中ViewControllerOne的代码也就是键盘的监听，代码如下：

   #import "ViewControllerOne.h"
   
   @interface ViewControllerOne ()
   
   @end
   
   @implementation ViewControllerOne
   
   - (void)viewDidLoad {
       [super viewDidLoad];
       // Do any additional setup after loading the view.
       [self obserKeyboard];
   }
   #pragma mark - 键盘的监控
   - (void)obserKeyboard {
       [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
       [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardShow:) name:UIKeyboardDidShowNotification object:nil];
   
       [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
   
       [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardHide:) name:UIKeyboardDidHideNotification object:nil];
   }
   #pragma mark 键盘动作
   - (void)keyboardWillShow:(NSNotification *)notif {
       NSLog(@"键盘将要弹出-keyboardWillShow");
   }
   - (void)keyboardShow:(NSNotification *)notif {
       NSLog(@"键盘已经弹出-keyboardShow");
   }
   - (void)keyboardWillHide:(NSNotification *)notif {
       NSLog(@"键盘将要隐藏-keyboardWillHide");
   }
   - (void)keyboardHide:(NSNotification *)notif {
       NSLog(@"键盘已经隐藏-keyboardWillHide");
   
   }

   当我们点击push进去的时候，我们再看控制台的打印信息。

4. 在ViewControllerOne里面也监测到了键盘的事件。

这个会在真机上造成当push进入下一个界面的时候，屏幕上会出现一条黑线从右划到左边。其实是键盘弹起又立马收回去的现象造成的，当然解决办法我目前是用的UIAlertViewController来代替。还说一点，其实为了解决这个问题，我当初还在点击确定按钮的时候用[self.view endEditing:YES];来防止键盘弹出，但是实际是没有卵用，键盘还是会弹出来，后来我全部换成了UIAlertViewController。