如果UITextField爲空，則顯示UIAlert

我想要做的，如果UITextField上沒有任何內容，應用程序將顯示警報。我不明白我在做什麼錯。這裏是我的代碼：如果UITextField爲空，則顯示UIAlert

- (IBAction)Calculate:(id)sender { 
    /*If there is nothing on textfield, it will show an alert*/ 

    if ([addtake.text length] && [Subtake.text length] == 0) 
    { 

      UIAlertView *myAlert = [[UIAlertView alloc]initWithTitle:@"Alert"message:@"Empty TextField not allowed" delegate:nil cancelButtonTitle:@"Okay" otherButtonTitles: nil];  
      [myAlert show]; 
    } 

    else{ 

      NSString *Adding =[addtake text]; 
      NSInteger number = [Adding intValue]; /*Converting String to int*/ 
      NSInteger new = 5 + number; 
      NSString *newString = [NSString stringWithFormat:@"%d",new]; 
      [myAdd setText:newString]; 
      /*Subtruct*/ 
      NSString *Subtruct =[Subtake text]; 
      NSInteger SubNumber = [Subtruct intValue]; 
      NSInteger newSub = 10 - SubNumber; 
      NSString *newSubString = [NSString stringWithFormat:@"%d",newSub]; 
      [mySub setText:newSubString]; 

      [addtake resignFirstResponder]; 
      [Subtake resignFirstResponder];   
     } 
    }

來源

2012-05-18 Adnan

其中textField？吸收或吸收？ – Shmidt

嘗試使每個子子句中的if語句明確的 - 如果僅僅是爲了便於閱讀...

我會用邏輯或，而不是邏輯並在測試。因此，如果任一文本字段爲空，警報將顯示

if ((![addtake.text length]) || (![Subtake.text length])) 
    { 

      UIAlertView *myAlert = [[UIAlertView alloc]initWithTitle:@"Alert"message:@"Empty TextField not allowed" delegate:nil cancelButtonTitle:@"Okay" otherButtonTitles: nil];  
      [myAlert show]; 
    }

來源

2012-05-18 07:58:04 Damo

是的，這是最好的解決方案:-) – Adnan

我認爲addText是你tesxField所以你需要設置的條件[addtake.text長度] == 0以及。

來源

2012-05-18 07:45:53 TompaLompa

if ([addtake.text length] == 0 && [Subtake.text length] == 0)

來源

2012-05-18 07:46:09 graver

如果UITextField爲空，則顯示UIAlert

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