顯示隱藏按鈕

Question

請耐心等待，因爲我仍在學習目標c的繩索。

我目前有一個按鈕，當按下隱藏iOS鍵盤。我想知道如何才能做到與此相反。當選擇文本字段時，鍵盤自動出現 - 同時，我希望此按鈕也出現在屏幕上。

謝謝！

-(IBAction)done:(id)sender{ 
//... 
//... 
[Screen resignFirstResponder]; 
done.hidden = YES; 
}; 

Answer 1

您將不得不使用NSNotification。實施addObserver在viewWillAppear中和removeObserver在viewWillDisappear

-(void)viewWillAppear:(BOOL)animated{ 
    [super viewWillAppear:animated]; 
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil]; 
} 

-(void)viewWillDisappear:(BOOL)animated{ 
    [super viewWillDisappear:animated]; 
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil]; 
} 

-(void)keyboardWillShow:(NSNotification*)notification{ 
    done.hidden = NO; 
} 

Answer 2

寄存器爲UIKeyboardWillShowNotification這樣的：

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil]; 

，並在顯示方法按鈕提供：

-(void) keyboardWillShow:(NSNotification*)notification{ 
    done.hidden = NO; 
} 

不要忘了與去除觀察員的dealloc

[[NSNotificationCenter defaultCenter] removeObserver:self]; 

Answer 3

您可以使用UITextFieldDelegate方法來實現這一目標，例如：

-(BOOL)textFieldShouldBeginEditing:(UITextField *)textField 
{ 
    done.hidden = NO;  
    return YES; 
} 

希望這將有助於。