当我加载一个UIView时,我如何在iPhone SDK上设置UITextField的最大字符数?
当前回答
斯威夫特4
import UIKit
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
}
}
编辑:内存泄漏问题修复。
其他回答
在Swift 5.2中工作:
class AngListVC: UIViewController, UITextFieldDelegate {
@IBOutlet weak var angTextField: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
angTextField.delegate = self
angTextField.addTarget(self, action: #selector(textFieldDidChange(_:)), for: .editingChanged)
}
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let userText = angTextField.text ?? ""
var newText = ""
if range.length > 0 {
let txt = NSString(string: userText)
if txt.length > 0 {
newText = txt.replacingCharacters(in: range, with: "")
}
} else {
newText = userText + ""
}
return newText.count <= 3
}
@objc func textFieldDidChange(_ textField: UITextField) {
print("textFieldDidChange")
}
斯威夫特4
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard let text = textField.text else { return true }
let newLength = text.count + string.count - range.length
return newLength <= 10
}
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
if (textField.text.length >= 50) {
return NO;
}
return YES;
}
适用于Swift 3.1或更高版本
首先添加协议UITextFieldDelegate
如:-
class PinCodeViewController: UIViewController, UITextFieldDelegate {
.....
.....
.....
}
之后创建你的UITextField并设置委托
完成经验:-
import UIKit
class PinCodeViewController: UIViewController, UITextFieldDelegate {
let pinCodetextField: UITextField = {
let tf = UITextField()
tf.placeholder = "please enter your pincode"
tf.font = UIFont.systemFont(ofSize: 15)
tf.borderStyle = UITextBorderStyle.roundedRect
tf.autocorrectionType = UITextAutocorrectionType.no
tf.keyboardType = UIKeyboardType.numberPad
tf.clearButtonMode = UITextFieldViewMode.whileEditing;
tf.contentVerticalAlignment = UIControlContentVerticalAlignment.center
return tf
}()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(pinCodetextField)
//----- setup your textfield anchor or position where you want to show it-----
// after that
pinCodetextField.delegate = self // setting the delegate
}
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
return !(textField.text?.characters.count == 6 && string != "")
} // this is return the maximum characters in textfield
}
现在你想要多少字符,只要给值就行了
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
NSUInteger newLength = [textField.text length] + [string length] - range.length;
return (newLength > 25) ? NO : YES;
}
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