Set the maximum character length of a UITextField

Question

How can I set the maximum amount of characters in a UITextField on the iPhone SDK when I load up a UIView?

Answer 1

The best way would be to set up a notification on the text changing. In your -awakeFromNib of your view controller method you'll want:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(limitTextField:) name:@"UITextFieldTextDidChangeNotification" object:myTextField];

Then in the same class add:

- (void)limitTextField:(NSNotification *)note {
    int limit = 20;
    if ([[myTextField stringValue] length] > limit) {
        [myTextField setStringValue:[[myTextField stringValue] substringToIndex:limit]];
    }
}

Then link up the outlet myTextField to your UITextField and it will not let you add any more characters after you hit the limit. Be sure to add this to your dealloc method:

[[NSNotificationCenter defaultCenter] removeObserver:self name:@"UITextFieldTextDidChangeNotification" object:myTextField];

Answer 2

swift 3.0

This code is working fine when you are paste string more than your character limits.

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        let str = (textView.text + text)
        if str.characters.count <= 10 {
            return true
        }
        textView.text = str.substring(to: str.index(str.startIndex, offsetBy: 10))
        return false
    }

Thanks for your votes. :)

Answer 3

You can't do this directly - UITextField has no maxLength attribute, but you can set the UITextField's delegate, then use:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string

Answer 4

Using Interface builder you can link and get the event for "Editing changed" in any of your function. Now there you can put check for the length

- (IBAction)onValueChange:(id)sender 
{
    NSString *text = nil;
    int MAX_LENGTH = 20;
    switch ([sender tag] ) 
    {
        case 1: 
        {
            text = myEditField.text;
            if (MAX_LENGTH < [text length]) {
                myEditField.text = [text substringToIndex:MAX_LENGTH];
            }
        }
            break;
        default:
            break;
    }

}

Answer 5

There is generic solution for setting max length in Swift. By IBInspectable you can add new Attribute in Xcode Attribute Inspector.

import UIKit
private var maxLengths = [UITextField: Int]()
extension UITextField {

    @IBInspectable var maxLength: Int {
        get {
            guard let length = maxLengths[self]
            else {
                return Int.max
            }
            return length
        }
        set {
            maxLengths[self] = newValue
            addTarget(
                self,
                action: Selector("limitLength:"),
                forControlEvents: UIControlEvents.EditingChanged
            )
        }
    }

    func limitLength(textField: UITextField) {
        guard let prospectiveText = textField.text
            where prospectiveText.characters.count > maxLength else {
                return
        }
        let selection = selectedTextRange
        text = prospectiveText.substringWithRange(
            Range<String.Index>(prospectiveText.startIndex ..< prospectiveText.startIndex.advancedBy(maxLength))
        )
        selectedTextRange = selection
    }

}

Answer 6

The Problem with some of the answer given above is, For example I have a text field and I have to set a limit of 15 characters input, then it stops after entering 15th Character. but they Don't allow to delete. That is the delete button also don't work. As I was facing the same problem. Came out with the solution , Given Below. Works Perfect for Me

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
 if(textField.tag==6)
 {
    if ([textField.text length]<=30)
    {
        return YES;   
    }
    else if([@"" isEqualToString:string])
    {
        textField.text=[textField.text substringToIndex:30 ];
    }

    return NO;
 }
 else
 {
    return YES;
 }
}

I am having a text field, whose tag I have set "6" and I have restricted the max char limit = 30 ; works fine in every case