UITextField-开头和结尾均不可编辑的前缀字符

Question

I have a UITextField, and I want to give it uneditable characters. For example I have "Hello..." , and I want the user to write in between o and . such as "Hello userTypedStuff..."

I used this approach, however with that, user can longpress the beginning and for example go to the position inside Hello. Thus, user can mess with the prefixed characters.

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    let protectedRange = NSMakeRange(0, 5)
    let intersection = NSIntersectionRange(protectedRange, range)
    if intersection.length > 0 {

        return false
    }
    if range.location == 12 {
        return true
    }
    if range.location + range.length > 12 {
        return false
    }
    return true
}

How can I setup something like 'uneditable first 5 characters and last 3 characters'?

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Edit: The UITextField's text-aligned center and is forming above a UILabel. However, if I give textField the width of label, textField won't get larger on width. Thus, I gave its width view's width. Is there a way I can create UILabel on both ends having Hello and ... separately, and have textField (with text-aligned center) in the middle which automatically stretches width?

---

Edit 2:

If I have my textview with two static UILabels on both sides, that can be a workaround. However, this time the UITextField won't push UILabels to sides as user starts to type in. The TextField center textAligned. If I give it a constant width while creating it (programatically with CGRectMake ) , it won't stretch its width as user types in. Thus, I gave it the width of view. Is there a way to auto-stretch the TextField's width as user types in that pushes the UILabels on the sides?

 "Hello" [textfield] "..."
 uilabel             uilabel

Answer 1

class SpecialTextField: UITextField {

// MARK: - UITextField Observing
override internal func willMoveToSuperview(newSuperview: UIView!) {
    if newSuperview != nil {
        text = "Hello..."
        addTarget(self, action: #selector(SpecialTextField.didChangeText), forControlEvents: .EditingChanged)
    }
}

override internal func canPerformAction(action: Selector, withSender sender: AnyObject?) -> Bool {
    return false
}


private var newVal: String = "Hello..."

func didChangeText() {
    var userDidEditDefaultValue = true
    if (text?.characters.count > 7) { // Count of "Hello..."
        if text?.rangeOfString("Hello") != nil {
            if text?.rangeOfString("...") != nil {
                userDidEditDefaultValue = false
            }
        }
    }
    if userDidEditDefaultValue {
        text = newVal
    }
    newVal = text ?? "Hello..."
}
}

This will not allow user to change default value of "Hello..." OR "Hello userEntry..."

You can use delegate method to insert text in the middle.

Hope it helped.