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

Use below extension for UITextField and UITextView character limits.

    private var kAssociationKeyMaxLength: Int = 0

    extension UITextField {


        @IBInspectable var maxLength: Int {
            get {
                if let length = objc_getAssociatedObject(self, &kAssociationKeyMaxLength) as? Int {
                    return length
                } else {
                    return Int.max
                }
            }
            set {
                objc_setAssociatedObject(self, &kAssociationKeyMaxLength, newValue, .OBJC_ASSOCIATION_RETAIN)
                addTarget(self, action: #selector(checkMaxLength), for: .editingChanged)
            }
        }

        @objc func checkMaxLength(textField: UITextField) {
            guard let prospectiveText = self.text,
                prospectiveText.count > maxLength
                else {
                    return
            }

            let selection = selectedTextRange

            let indexEndOfText = prospectiveText.index(prospectiveText.startIndex, offsetBy: maxLength)
            let substring = prospectiveText[..<indexEndOfText]
            text = String(substring)

            selectedTextRange = selection
        }
    }

    extension UITextView:UITextViewDelegate {


    @IBInspectable var maxLength: Int {
        get {
            if let length = objc_getAssociatedObject(self, &kAssociationKeyMaxLength) as? Int {
                return length
            } else {
                return Int.max
            }
        }
        set {
            self.delegate = self

            objc_setAssociatedObject(self, &kAssociationKeyMaxLength, newValue, .OBJC_ASSOCIATION_RETAIN)
        }
    }

    public func textViewDidChange(_ textView: UITextView) {
        checkMaxLength(textField: self)
    }
    @objc func checkMaxLength(textField: UITextView) {
        guard let prospectiveText = self.text,
            prospectiveText.count > maxLength
            else {
                return
        }

        let selection = selectedTextRange

        let indexEndOfText = prospectiveText.index(prospectiveText.startIndex, offsetBy: maxLength)
        let substring = prospectiveText[..<indexEndOfText]
        text = String(substring)

        selectedTextRange = selection
    }
}

You can set limit below.

Answer 2

Got it down to 1 line of code :)

Set your text view's delegate to "self" then add the <UITextViewDelegate> in your .h and the following code in your .m .... you can adjust the number "7" to be whatever you want your MAXIMUM number of characters to be.

-(BOOL)textView:(UITextView *)a shouldChangeTextInRange:(NSRange)b replacementText:(NSString *)c {
    return ((a.text.length+c.length<=7)+(c.length<1)+(b.length>=c.length)>0);
}

This code accounts for typing new characters, deleting characters, selecting characters then typing or deleting, selecting characters and cutting, pasting in general, and selecting characters and pasting.

Done!

---

Alternatively, another cool way to write this code with bit-operations would be

-(BOOL)textView:(UITextView *)a shouldChangeTextInRange:(NSRange)b replacementText:(NSString *)c {
    return 0^((a.text.length+c.length<=7)+(c.length<1)+(b.length>=c.length));
}

Answer 3

I created this UITextFieldLimit subclass:

• Multiple textfields supported
• Set the text length limit
• Paste prevention
• Displays a label of left characters inside the textfield, get hidden when you stop editing.
• Shake animation when no characters left.

Grab the UITextFieldLimit.h and UITextFieldLimit.m from this GitHub repository:

https://github.com/JonathanGurebo/UITextFieldLimit

and begin to test!

Mark your storyboard-created UITextField and link it to my subclass using the Identity Inspector:

Then you can link it to an IBOutlet and set the limit(default is 10).

---

Your ViewController.h file should contain: (if you wan't to modify the setting, like the limit)

#import "UITextFieldLimit.h"

/.../

@property (weak, nonatomic) IBOutlet UITextFieldLimit *textFieldLimit; // <--Your IBOutlet

---

Your ViewController.m file should @synthesize textFieldLimit.

---

Set the text length limit in your ViewController.m file:

- (void)viewDidLoad
{
    [super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

    [textFieldLimit setLimit:25];// <-- and you won't be able to put more than 25 characters in the TextField.
}

Hope the class helps you. Good luck!

Answer 4

To make it work with cut & paste of strings of any length, I would suggest changing the function to something like:

#define MAX_LENGTH 20

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
    {
        NSInteger insertDelta = string.length - range.length;

        if (textField.text.length + insertDelta > MAX_LENGTH)
        {
           return NO; // the new string would be longer than MAX_LENGTH
        }
        else {
            return YES;
        }
    }

Answer 5

Thank you august! (Post)

This is the code that I ended up with which works:

#define MAX_LENGTH 20

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if (textField.text.length >= MAX_LENGTH && range.length == 0)
    {
        return NO; // return NO to not change text
    }
    else
    {return YES;}
}

Answer 6

Other answers do not handle the case where user can paste a long string from clipboard. If I paste a long string it should just be truncated but shown. Use this in your delegate:

static const NSUInteger maxNoOfCharacters = 5;

-(IBAction)textdidChange:(UITextField * )textField
{
NSString * text = textField.text;

if(text.length > maxNoOfCharacters)
{
    text = [text substringWithRange:NSMakeRange(0, maxNoOfCharacters)];
    textField.text = text;
}

// use 'text'

}