我想要自定义的UITextfield，它具有与android相同的占位符行为，我也想要UITextfield中的错误标签。
最近我在android中见过。它们具有默认的文本区域，在该区域中，用户开始书写时不会隐藏占位符，而不是隐藏它们，而是使占位符位于textarea上方。
最佳答案
最近，我创建了与您的需求相同的CustomTextfield类。
这是Github链接，用于下载类及其用法https://github.com/indrajitv/CustomTextField
下面是代码，
//
// 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:
关于ios - 我想要具有与Android相同的占位符行为的自定义UITextfield，也想要UITextfield中的错误标签，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/51894057/