TextFieldShould中的UIAlertcontroller应该开始编辑Objective-C

Question

I want to show alert before text enter in textfield after ok button click textfield will be editable but I am showing alert but textfield did not editable.

if(textField == contractValueField)
{
    [self showAlertWithTitle:@"Information" textfield:contractValueField];
    return YES;
}

I search so many sites but I did not get right answer by using UIAlertView it is working but I want to use UIAlertController. I have more than 20 textfields in my project & every textfield I will show alert before edit begin.

- (void)showAlertWithTitle:(NSString *)title textfield:(UITextField*)textfield
{
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:title message:@"Please enter Amount in Lakhs" preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction* ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action)
    {
        [alert dismissViewControllerAnimated:YES completion:nil];
        [textfield becomeFirstResponder];
    }];

    [alert addAction:ok];
    [self.navigationController presentViewController:alert animated:YES completion:nil];
}

Answer 1

The reason is that when you call [textfield becomeFirstResponder] , -(BOOL)textFieldShouldBeginEditing:(UITextField *)textField is also called again, which in turn shows your alertView, and when the ok button is selected from your alert, the alert view is shown again, and you are stuck in a loop. Here is a quick way to fix it:

-(BOOL)textFieldShouldBeginEditing:(UITextField *)textField{
    // check to see if the alert has already been shown, if it has the tag value will be 1
    if (textField == contractValueField && textField.tag != 1) {
        [self showAlertWithTitle:@"Information" textfield:textField];
        return false;
    }
    return true;
}

The code for your alertView should be as follows:

- (void)showAlertWithTitle:(NSString *)title textfield:(UITextField*)textfield{
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:title message:@"Please enter Amount in Lakhs" preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction* ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action){
        textfield.tag = 1;
        [alert dismissViewControllerAnimated:YES completion:nil];
        [textfield becomeFirstResponder];
    }];

    [alert addAction:ok];
    [self presentViewController:alert animated:true completion:nil];
}

Return the tag value of textField back to 0 when editing is finished:

-(BOOL)textFieldShouldEndEditing:(UITextField *)textField{
    textField.tag = 0;
    return true;
}

Answer 2

Declare a UITextField which will reference the last selected textField:

@interface ViewController (){
    UITextField *lastSelectedTextField;
}

-(BOOL)textFieldShouldBeginEditing:(UITextField *)textField{
    // check to see if the textField is the last shown textField
    if (textField == lastSelectedTextField) {
        return true;
    }
    [self showAlertWithTitle:@"Information" textfield:textField];
    return false;
 }


- (void)showAlertWithTitle:(NSString *)title textfield:(UITextField*)textfield{
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:title message:@"Please enter Amount in Lakhs" preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction* ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action){
        lastSelectedTextField = textfield;;
        [alert dismissViewControllerAnimated:YES completion:nil];
        [textfield becomeFirstResponder];
    }];

    [alert addAction:ok];
    [self presentViewController:alert animated:true completion:nil];
}

This would be the better option, I didn't realise that you wanted to show the alert every even if the textField had been selected previously