Question

UITextField为空时的值是多少？我似乎无法做到这一点。

我试过了（其中`phraseBox'是所说的UITextField的名字

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

和

if(phraseBox.text != nil){

我错过了什么？

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

在搜索同样的东西时在苹果讨论中找到了这个，想到这里也发布了不好意思。检查字符串的长度：

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

}

或者在验证之前可以选择修剪它的空格，这样用户就不能输入空格了。对于用户名来说很好。

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

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

Answer 3

尝试以下代码

textField.text是一个字符串值，所以我们像这样检查它

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

{

// There's no text in the box.

}

else

{

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

}

Answer 4

-(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 5

实际上，我使用Raphael的方法遇到了多个文本字段的问题。这就是我想出的：

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

Answer 6

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 7

验证空UITextfield。如果您不希望UITextField不接受空白空格。使用此代码段：

- (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;
    }
}

验证空的UITextField？

7 个答案: