UITextField clear when selected, but also restore data if nothing is input

问题

I have a table with UITextFields, and I want to make it so that when a textfield is selected, the current info is cleared (to allow new input), but if the user decides (after selecting) that they don't want to change it, I want them to be able to click elsewhere and the data from before reappears in the textfield.

Is there an easy way to do this?

回答1:

A good way to do this that's nice and user friendly is to use the placeholder property. Set up your viewController as the textfield's delegate (as described by Andeh) then add the following code:

- (void)textFieldDidBeginEditing:(UITextField *)textField {
    textField.placeholder = textField.text;
    textField.text = @"";
}

- (void)textFieldDidEndEditing:(UITextField *)textField {
    if (textField.text.length == 0) {
        textField.text = textField.placeholder;
    }
    textField.placeholder = @"";
}

And you're done. If you have multiple UITextFields on the page and you don't want this behaviour for all of them you can add a check to the methods above.

回答2:

In the textFieldDidBeginEditing delegate method, save the current value to a persisting variable before clearing the UITextField. Then in the didFinishEditing delegate method, if the new length of the user input is 0 set the text back to the stored value!

UITextField Delegate docs for reference.

回答3:

First I think you have two sets of behaviors here.

The text field must clear the value when you begin editing. This exists: -clearsOnBeginEditing.
The text field must restore the previous text if text is empty. Subclassing seems the better solution.

Here is a possible sample class:

// MyRestoringTextField.h
@interface MyRestoringTextField : UITextField
@end

// MyTextField.m
@interface MyRestoringTextField ()
@property (strong, nonatomic) NSString *previousText;
@end

@implementation MyRestoringTextField
- (BOOL)becomeFirstResponder
{
    BOOL result = [super becomeFirstResponder];
    self.previousText = self.text;
    return result;
}
- (BOOL)resignFirstResponder
{
    BOOL result = [super resignFirstResponder];
    if (self.text.length == 0)
        self.text = self.previousText;
    return result;
}
@end

Hope that helps.

回答4:

To clear and then restore a textField if you fail to make an entry, use the following delegates as such:

-(void)textFieldDidBeginEditing:(UITextField *)textField
{
   [[NSUserDefaults standardUserDefaults] setObject:textField.text forKey:kTextFieldIdentifier];
    textField.text = @"";
}

-(BOOL)textFieldShouldEndEditing:(UITextField *)textField
{
    if ([textField.text isEqualToString:@""])
        textField.text  = [[NSUserDefaults standardUserDefaults]
                    stringForKey:kTextFieldIdentifier];
    return YES;
}

回答5:

As of iOS 8.1, textFieldDidBeginEditing is already receiving a cleared text. You should use

-(BOOL) textFieldShouldBeginEditing:(UITextField *)textField

to initialized the placeholder field.

来源：https://stackoverflow.com/questions/12169145/uitextfield-clear-when-selected-but-also-restore-data-if-nothing-is-input

标签

ios

uitextfield