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我对 iOS 7.1.2 上的 UITextField 使用 iPhone4S 进行了一些练习。

界面：

第一个版本的界面很简单，只是有一个自定义的UITextField命名MyUITextField和一个UIButtom用于取消搜索操作的对象。在 textField 内部，它的leftView属性最初设置为一个UIButton对象，该对象的背景图像是一个放大镜。当用户在 textField 中点击时，该放大镜按钮将被移除，并且 leftView 属性也将设置为一个新的 UIButton 对象，该对象的背景图像是一个倒三角形。当用户点击三角形按钮时，应用程序将创建一个新的视图对象。

主要代码：

//In this version,the textField's original frame property is set to (10,40,250,30) 
//and the main operations are like this:

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.myTextField.delegate = self;
    self.myTextField.leftViewMode = UITextFieldViewModeUnlessEditing;
    self.myTextField.leftView = [self creCustomSearchBar];

    [[NSNotificationCenter defaultCenter] addObserver:self  
                                             selector:@selector(keyBoardWillAppear:) 
                                                 name:@"UIKeyboardWillShowNotification" 
                                               object:nil];
    [self.cancleSearchButton addTarget:self 
                                action:@selector(cancleSearch:) 
                      forControlEvents:UIControlEventTouchUpInside];
}

/*when tapping in the textField,keyboard will appear*/
- (void)keyBoardWillAppear:(NSNotification *)notification
{
    CGRect newLeftViewIndicatorRect = CGRectMake(20,5,20,20);
    UIButton *newLeftViewIndicator = [[UIButton alloc] initWithFrame:newLeftViewIndicatorRect];
    NSString *imagePath = [[NSBundle mainBundle] pathForResource:@"searchbar_textfield_down_icon@2x" ofType:@"png"];

    [newLeftViewIndicator setBackgroundImage:[UIImage imageWithContentsOfFile:imagePath] forState:UIControlStateNormal];
    [newLeftViewIndicator addTarget:self action:@selector(createActuralLeftView:) forControlEvents:UIControlEventTouchUpInside];

    self.myTextField.leftView = newLeftViewIndicator;
    /*in the second verson need to call */
    //[self adjustViewFrame];
    [self.cancleSearchButton setTitle:@"取消" forState:UIControlStateNormal];
}

- (void)createActuralLeftView:(UIButton *)leftViewButton
{
    UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self
                                                     action:@selector(tapRegionAboveKeyboard:)];
    [self.view addGestureRecognizer:tapGesture];
    NewLeftView *leftView = [[NewLeftView alloc] initWithFrame:CGRectMake(10, 80, 140, 100)];
    leftView.delegate = self;
    [self.view addSubview:leftView];
}

- (void)tapRegionAboveKeyboard:(UITapGestureRecognizer *)tapGesture
{
    for (UIView *v  in self.view.subviews) {
        if ([v isKindOfClass:[NewLeftView class]]) {
            [v removeFromSuperview];
            [self.view removeGestureRecognizer:tapGesture];
            return;
        }
    }
}

//in the second version need to call 
- (void)adjustViewFrame
{
    [[self.myTextField class] animateWithDuration:0.05 animations:^{
        [self.myTextField setFrame:CGRectMake(self.myTextField.frame.origin.x, 40, self.myTextField.frame.size.width, self.myTextField.frame.size.height)];
    }];
    [[self.cancleSearchButton class] animateWithDuration:0.05 animations:^{
        [self.cancleSearchButton setFrame:CGRectMake(self.cancleSearchButton.frame.origin.x, 40, self.cancleSearchButton.frame.size.width, self.cancleSearchButton.bounds.size.height)];
    }];
}

在第一个版本中，一切正常。

但是在第二个版本中，我将textField frame 属性设置为(10,260,250,30)，所以我需要调用中的adjustViewFrame方法keyBoardWillAppear:来重新定位textField，以防被键盘遮挡。

问题来了：textField的位置正确移动到正确的位置，但是当我点击倒三角形按钮时，textField消失了。

我无法弄清楚这里出了什么问题。

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