驗證空UITextField？

Question

UITextField空時的值是什麼？我似乎無法得到這個權利。

我試過（其中`phraseBox」它所說的UITextField

if(phraseBox.text != @""){ 

和

if(phraseBox.text != nil){

我缺少什麼？

Answer 1

// Check to see if it's blank 
if([phraseBox.text isEqualToString:@""]) { 
    // There's no text in the box. 
} 

// Check to see if it's NOT blank 
if(![phraseBox.text isEqualToString:@""]) { 
    // There's text in the box. 
} 

Answer 2

嘗試名以下代碼

的TextField.text是一個字符串值，所以我們正在檢查它像​​這樣

if([txtPhraseBox.text isEqualToString:@""]) 

{ 

// There's no text in the box. 

} 

else 

{ 

NSLog(@"Text Field Text == : %@ ",txtPhraseBox.text); 

} 

Answer 3

同樣的事情在搜索時發現這個在蘋果討論

，以爲生病後在這裏了。 檢查字符串的長度：

NSString *value = textField.text; 
if([value length] == 0) { 

} 

或任選驗證之前從它修剪空格，所以用戶不能輸入空格instead.works以及爲用戶名。

NSString *value = [textField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]; 

if([value length] == 0) { 
// Alert the user they forgot something 
} 

Answer 4

事實上，我遇到了使用拉斐爾的方法與多個文本字段的輕微問題。以下是我想出了：

if ((usernameTextField.text.length > 0) && (passwordTextField.text.length > 0)) { 
    loginButton.enabled = YES; 
} else { 
    loginButton.enabled = NO; 
} 

Answer 5

用於文本字段驗證：

-(BOOL)validation{ 
if ([emailtextfield.text length] <= 0) { 
    [UIAlertView showAlertViewWithTitle:AlertTitle message:AlertWhenemailblank]; 
    return NO; } 
return YES;} 

Answer 6

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{ 

    NSString *fullText = [textField.text stringByAppendingString:string];  
    if ((range.location == 0) && [self isABackSpace:string]) { 
    //the textFiled will be empty 
    } 
    return YES; 
} 

-(BOOL)isABackSpace:(NSString*)string { 
    NSString* check =@"Check"; 
    check = [check stringByAppendingString:string]; 
    if ([check isEqualToString:@"Check"]) { 
    return YES; 
    } 
    return NO; 
} 

Answer 7

驗證對空的UITextField。如果你不希望那個UITextField不應該接受空白的空格。使用此代碼片段：

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string { 

    NSString *resultingString = [textField.text stringByReplacingCharactersInRange: range withString: string]; 
    NSCharacterSet *whitespaceSet = [NSCharacterSet whitespaceCharacterSet]; 
    if ([resultingString rangeOfCharacterFromSet:whitespaceSet].location == NSNotFound)  { 
     return YES; 
    } else { 
     return NO; 
    } 
}