我想要定制的UITextfield，其占位符行为与android相同，我也想在UITextfield中使用错误标签
我想要定制的UITextfield ，其占位符行为与android相同，我也想在UITextfield中使用错误标签。
最近我在android中看到过。 它们具有默认文本区域，其中当用户开始写入时占位符不会被隐藏，而不是隐藏它们使得占位符保持在textarea的上方。
最近我创建了我的CustomTextfield类，它与您的要求相同。
这是下载类及其用法的Github链接https://github.com/indrajitv/CustomTextField
以下是代码，
// // File.swift // customTextField // // Created by indrajit on 17/08/18. // Copyright © 2018 indrajit. All rights reserved. // import UIKit @IBDesignable open class CustomTextField:UITextField{ private var labelPlaceholderTitleTop:NSLayoutConstraint! private var labelPlaceholderTitleCenterY:NSLayoutConstraint! private var labelPlaceholderTitleLeft:NSLayoutConstraint! @IBInspectable var allowToShrinkPlaceholderSizeOnEditing = true @IBInspectable var shrinkSizeOfPlaceholder:CGFloat = 0 @IBInspectable var placeHolderColor:UIColor = .lightGray{ didSet{ labelPlaceholderTitle.textColor = placeHolderColor } } open override var font: UIFont?{ didSet{ labelPlaceholderTitle.font = font } } @IBInspectable var heightOfBottomLine:CGFloat = 1{ didSet{ heightAnchorOfBottomLine.constant = heightOfBottomLine } } open override var leftView: UIView?{ didSet{ if let lv = leftView{ labelPlaceholderTitleLeft.constant = lv.frame.width+leftPadding } } } @IBInspectable var leftPadding:CGFloat = 0{ didSet{ labelPlaceholderTitleLeft.constant = leftPadding } } @IBInspectable var errorText:String = ""{ didSet{ self.labelError.text = errorText } } @IBInspectable var errorColor:UIColor = .red{ didSet{ labelError.textColor = errorColor } } @IBInspectable var errorFont:UIFont = UIFont.systemFont(ofSize: 10){ didSet{ self.labelError.font = errorFont } } @IBInspectable var shakeIntensity:CGFloat = 5 private var heightAnchorOfBottomLine:NSLayoutConstraint! lazy var labelPlaceholderTitle:UILabel={ let label = UILabel() label.numberOfLines = 0 label.translatesAutoresizingMaskIntoConstraints = false label.font = self.font label.adjustsFontSizeToFitWidth = true return label }() lazy var labelError:UILabel={ let label = UILabel() label.numberOfLines = 0 label.translatesAutoresizingMaskIntoConstraints = false label.adjustsFontSizeToFitWidth = true label.text = self.errorText label.textAlignment = .right label.font = self.errorFont label.textColor = errorColor return label }() let bottonLineView:UIView={ let view = UIView() view.backgroundColor = .red view.translatesAutoresizingMaskIntoConstraints = false return view }() override init(frame: CGRect) { super.init(frame: frame) self.initalSetup() } required public init?(coder aDecoder: NSCoder) { super.init(coder: aDecoder) self.initalSetup() } override open func prepareForInterfaceBuilder() { self.initalSetup() } open override func awakeFromNib() { self.labelError.isHidden = true } func initalSetup(){ self.labelPlaceholderTitle.text = placeholder placeholder = nil borderStyle = .none bottonLineView.removeFromSuperview() addSubview(bottonLineView) bottonLineView.leftAnchor.constraint(equalTo: leftAnchor, constant: 0).isActive = true bottonLineView.rightAnchor.constraint(equalTo: rightAnchor, constant: 0).isActive = true bottonLineView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: 0).isActive = true heightAnchorOfBottomLine = bottonLineView.heightAnchor.constraint(equalToConstant: heightOfBottomLine) heightAnchorOfBottomLine.isActive = true addSubview(labelPlaceholderTitle) labelPlaceholderTitleLeft = labelPlaceholderTitle.leftAnchor.constraint(equalTo: leftAnchor, constant: leftPadding) labelPlaceholderTitleLeft.isActive = true labelPlaceholderTitle.rightAnchor.constraint(equalTo: rightAnchor, constant: 0).isActive = true labelPlaceholderTitleTop = labelPlaceholderTitle.topAnchor.constraint(equalTo: topAnchor, constant: 0) labelPlaceholderTitleTop.isActive = false labelPlaceholderTitleCenterY = labelPlaceholderTitle.centerYAnchor.constraint(equalTo: centerYAnchor, constant: 0) labelPlaceholderTitleCenterY.isActive = true addSubview(labelError) labelError.leftAnchor.constraint(equalTo: leftAnchor, constant: 0).isActive = true labelError.rightAnchor.constraint(equalTo: rightAnchor, constant: 0).isActive = true labelError.topAnchor.constraint(equalTo: bottonLineView.bottomAnchor, constant: 2).isActive = true addTarget(self, action: #selector(self.textFieldDidChange), for: .editingChanged) } @objc func textFieldDidChange(){ func animateLabel(){ UIView.animate(withDuration: 0.2, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations: { self.layoutIfNeeded() }, completion: nil) } if let enteredText = text,enteredText != ""{ if labelPlaceholderTitleCenterY.isActive{ labelPlaceholderTitleCenterY.isActive = false labelPlaceholderTitleTop.isActive = true labelPlaceholderTitleTop.constant = -5 if allowToShrinkPlaceholderSizeOnEditing{ let currentFont = font == nil ? UIFont.systemFont(ofSize: 16) : font! let shrinkSize = shrinkSizeOfPlaceholder == 0 ? currentFont.pointSize-3 : shrinkSizeOfPlaceholder labelPlaceholderTitle.font = UIFont.init(descriptor: currentFont.fontDescriptor, size:shrinkSize) } animateLabel() } }else{ labelPlaceholderTitleCenterY.isActive = true labelPlaceholderTitleTop.isActive = false labelPlaceholderTitleTop.constant = 0 labelPlaceholderTitle.font = font animateLabel() } } @objc public func showError(){ self.labelError.isHidden = false let animation = CABasicAnimation(keyPath: "position") animation.duration = 0.07 animation.repeatCount = 4 animation.autoreverses = true animation.fromValue = NSValue(cgPoint: CGPoint(x: center.x - shakeIntensity, y: center.y)) animation.toValue = NSValue(cgPoint: CGPoint(x: center.x + shakeIntensity, y: center.y)) layer.add(animation, forKey: "position") } @objc public func hideError(){ self.labelError.isHidden = true } }
**用法：
// // ViewController.swift // customTextField // // Created by indrajit on 16/08/18. // Copyright © 2018 indrajit. All rights reserved. // import UIKit class ViewController: UIViewController { @IBOutlet weak var text: CustomTextField! override func viewDidLoad() { super.viewDidLoad() } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } @IBAction func okClicked(_ sender: UIButton) { if text.text! == ""{ text.showError() }else{ text.hideError() } } }
输出：
