textFieldShouldBeginEditing + UIKeyboardWillShowNotification + OS 3.2

Question

我在UIView上有多个文本字段.

我在textFieldShouldBeginEditing方法中退出前一个textField,执行以下事件序列

• 收到对应于隐藏前一个字段的键盘的字段的UIKeyboardWillHideNotification.

• 方法textFieldShouldBeginEditing返回YES然后

• 收到UIKeyboardWillShowNotification,显示当前字段的键盘.

但是,在OS 3.2中,即使textFieldShouldBeginEditing返回YES,也不会收到当前字段的UIKeyboardWillShowNotification.

该逻辑适用于OS <3.2

我可能做错了什么想法？

列在我的代码的一部分下面(xib中只有两个文本字段).

我需要在keyboardWillShow和keyboardWillHide上执行一组操作查看在OS 3.2和OS <3.2中运行代码的区别

任何人都可以解释行为上的差异吗？

.H

@interface ExampleViewController : UIViewController  
{
    IBOutlet UITextField *numericTextField;
    IBOutlet UITextField *alphaTextField;   
    UITextField *lastTextField;
    int lastCursorPos;
    int cursorPosition;
    NSMutableArray *textFields;
}

@property (nonatomic, retain) UITextField *lastTextField;
@property (nonatomic, retain) NSMutableArray *textFields;

@end

.M

- (void)viewWillAppear:(BOOL)animated
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) 
                                                 name:UIKeyboardWillShowNotification object:self.view.window]; 
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) 
                                                 name:UIKeyboardWillHideNotification object:self.view.window]; 

    self.view.backgroundColor = [UIColor groupTableViewBackgroundColor];
    self.textFields = [[NSMutableArray alloc] initWithCapacity:2];
    [self.textFields insertObject:alphaTextField atIndex:0];
    [self.textFields insertObject:numericTextField atIndex:1];
    cursorPosition = 1;
    [numericTextField becomeFirstResponder];
}

-(void)viewWillDisappear:(BOOL)animated 
{
    [self setEditing:NO animated:YES];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil]; 
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil]; 
}

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField 
{
    int index;
    for(UITextField *aField in self.textFields){

        if (textField == aField){
            index = [self.textFields indexOfObject:aField];
        }
    }
    if(index>=0 ){
        lastCursorPos = cursorPosition;
        self.lastTextField = [self.textFields objectAtIndex:lastCursorPos-1];
        cursorPosition = index +1;

    }
    [self.lastTextField resignFirstResponder];  

    return YES;
}

- (BOOL)textFieldShouldEndEditing:(UITextField *)textField {        
    return YES;
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    [textField resignFirstResponder];
    return YES; 
}

- (void)keyboardWillShow:(NSNotification *)notif {
    NSLog(@"Inside keyboardWillShow");
}

- (void)keyboardWillHide:(NSNotification *)notif {      
    NSLog(@"Inside keyboardWillHide");
}

Answer 1

我相信从 iOS 3.2 开始，在两个文本字段之间切换时不再触发 UIKeyboardWillHideNotification 和 UIKeyboardWillShowNotification。基本上，仅当键盘实际显示或隐藏时才会触发通知，并且由于从一个文本字段切换到另一个文本字段不会隐藏键盘，因此不会触发该事件。

在 iOS 3.2 之前，每当您更改字段时都会触发事件。新方法可以说更正确，但它确实使您尝试做的事情更具挑战性。

您可能最好实现文本字段的委托，然后您可以检查 shouldBeginEditing/didEndEditing 事件，或者，您可以子类化 UITextField 并重写 comeFirstResponder/resignFirstResponder 方法，以便您可以挂钩它们并在以下情况下实现您的逻辑：场域接收和失去焦点。