问题
I want to create a max length to my textfield with IBInspectable
, I see a answer to this on a question here but I'm getting an error saying Expression type '()' is ambiguous without more context
,
My code was
import UIKit
private var __maxLengths = [UITextField: Int]()
extension UITextField {
@IBInspectable var maxLength: Int {
get {
guard let l = __maxLengths[self] else {
return 150 // (global default-limit. or just, Int.max)
}
return l
}
set {
__maxLengths[self] = newValue
addTarget(self, action: #selector(fix), for: .editingChanged)
}
}
@objc func fix(textField: UITextField) {
let t = textField.text
textField.text = t?.prefix(maxLength)
}
}
and I'm getting an error pointing at textField.text = t?.prefix(maxLength)
with an error message saying Expression type '()' is ambiguous without more context
,
How can I resolve it?
回答1:
In Swift 5, String's prefix
method returns a value of type String.SubSequence
func prefix(_ maxLength: Int) -> Substring
You'll need to convert this to a String
type.
One way to do this might be:
let s = textField.text!.prefix(maxLength) // though UITextField.text is defined as an optional String, can be safely force-unwrapped as the default value is an empty string even when set to nil
textField.text = String(s)
or if you prefer a single-line solution:
textField.text = String(textField.text!.prefix(maxLength))
来源:https://stackoverflow.com/questions/62165247/create-max-character-length-in-uitextfield-using-ibinspectable