验证空UITextField？

Question

UITextField空时的值是什么？我似乎无法得到这个权利。

我试过（其中`phraseBox”它所说的UITextField

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

和

if(phraseBox.text != nil){

我缺少什么？

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

尝试名以下代码

的TextField.text是一个字符串值，所以我们正在检查它像​​这样

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

{ 

// There's no text in the box. 

} 

else 

{ 

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

} 

Answer 3

同样的事情在搜索时发现这个在苹果讨论

，以为生病后在这里了。 检查字符串的长度：

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

} 

或任选验证之前从它修剪空格，所以用户不能输入空格instead.works以及为用户名。

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

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

Answer 4

事实上，我遇到了使用拉斐尔的方法与多个文本字段的轻微问题。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

用于文本字段验证：

-(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

验证对空的UITextField。如果你不希望那个UITextField不应该接受空白的空格。使用此代码片段：

- (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; 
    } 
}