UITextView標籤中的佔位符不會消失

我知道這裏有很多關於UITextView佔位符的鏈接，我嘗試了爲我工作的那個，但我不工作。即使當我開始在textView中輸入時，他們的佔位符文本仍然存在。任何人有任何想法，爲什麼？下面粘貼了我的代碼。UITextView標籤中的佔位符不會消失

AddExerciseViewController.m

#import "AddExerciseViewController.h" 

@implementation AddExerciseViewController 
@synthesize nameTextField = _nameTextField; 
@synthesize descriptionTextView = _descriptionTextView; 
@synthesize placeholderLabel = _placeholderLabel; 

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
{ 
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; 
    if (self) {  
    } 
    return self; 
} 

- (void)viewDidLoad 
{ 
    _descriptionTextView.layer.borderWidth = 3.0f; 
    _descriptionTextView.layer.borderColor = [[UIColor grayColor ] CGColor]; 
    _descriptionTextView.layer.cornerRadius = 5; 
    _descriptionTextView.clipsToBounds = YES; 

    _placeholderLabel = [[UILabel alloc] initWithFrame:CGRectMake(10.0, 0.0,   _descriptionTextView.frame.size.width - 20.0, 34.0)]; 
    [_placeholderLabel setText: @"FooBar"]; 

    // placeholderLabel is instance variable retained by view controller 
    [_placeholderLabel setBackgroundColor:[UIColor clearColor]]; 
    [_placeholderLabel setTextColor:[UIColor lightGrayColor]]; 

    [_descriptionTextView addSubview:_placeholderLabel]; 
    [super viewDidLoad]; 
} 

- (void) textViewDidChange:(UITextView *)theTextView 
{ 
    if(![_descriptionTextView hasText]) { 
    [_descriptionTextView addSubview:_placeholderLabel]; 
    [UIView animateWithDuration:0.15 animations:^{ 
     _descriptionTextView.alpha = 1.0; 
    }]; 
} else if ([[_descriptionTextView subviews] containsObject:_placeholderLabel]) { 

    [UIView animateWithDuration:0.15 animations:^{ 
     _placeholderLabel.alpha = 0.0; 
    } completion:^(BOOL finished) { 
     [_placeholderLabel removeFromSuperview]; 
    }]; 
} 
} 


- (void)textViewDidEndEditing:(UITextView *)theTextView 
{ 
    if (![_descriptionTextView hasText]) { 
     [_descriptionTextView addSubview:_placeholderLabel]; 
     [UIView animateWithDuration:0.15 animations:^{ 
      _placeholderLabel.alpha = 1.0; 
     }]; 
    } 
} 

- (void)viewDidUnload 
{ 
    [self setDescriptionTextView:nil]; 
    [self setNameTextField:nil]; 
    [super viewDidUnload]; 
}

@end

來源

2012-03-21 Niels Sønderbæk

我相信textViewDidChange:被編輯完成後才能調用。您可能想要改爲在textViewDidBeginEditing:上隱藏佔位符。

來源

2012-03-21 22:31:08 MechEthan

我不確定你的意思是什麼？ – 2012-03-21 22:52:12

您粘貼的代碼在用戶將文本輸入到UITextView時不會工作。 ' - （void）textViewDidChange：（UITextView *）theTextView {...}'只有在選擇另一個字段或隱藏鍵盤之後纔會被調用。 'textViewDidBeginEditing：'將在用戶開始輸入時立即調用UITextView的。 – MechEthan 2012-03-21 23:25:22

這很有道理。我想通過另一種方式來做到這一點。我只是添加了一個觀察者'UITextViewTextDidBeginEditingNotification'，並且這個函數刪除了佔位符，一旦該通知被調用:) – 2012-03-21 23:34:16

UITextView標籤中的佔位符不會消失

回答

相關問題