这和技术没关系，输入框设计-非原创

最近做项目竟然遇见了和这个差不多的需求，但是更全面，我根据这个的写法做了一个输入框，自我感觉良好，更新在这里，下面是效果图。

pwdField.gif

下载链接：https://pan.baidu.com/s/1n2yYS98sZ7xV99YjrtbFZQ

-------------------------割一下------------------------
这个实在网上看到的。
输入框是比较常用的，特别注册登录，填写信息什么的
我们都知道输入框有个属性placeholder相当于对输入有一个提示作用但是已输入就不见了，有的时候输入一半忘记输入提示是什么了。（记性不好的悲哀），也有些在上面设计一个提示一直存在这样看着页面有不简洁。
最近看到个设计在输入的时候把placeholder变小在输入框上面显示，觉得很好很实用。想这样

Untitled.gif

这样设计上可以留出上面提示的内容简介明了

做法很简单，自定义一个View，上面放上一个textField和一个label，然后根据textField当前的文字来判断label出现和消失。非常简单就不说代码了。直接放在下面给和我一样懒的人拷贝吧。嘿嘿

import UIKit

class SweetTextField: UIView, UITextFieldDelegate {
    
    var textStr:NSString {
        get{
            return NSString(string: textField.text!)
        }
    }
    var placeHolderStr:String {
        set{
            textField.placeholder = newValue as String
            showView.text = newValue as String
        }
        get{
            return self.placeHolderStr
        }
    }
    
    private let textField = UITextField()
    private let showView = UITextField()

    override init(frame: CGRect) {
        super.init(frame: frame)
        textField.frame = CGRect(x: 0, y: 0.2*bounds.height, width: bounds.width, height: 0.8*bounds.height)
        textField.delegate = self
        textField.textColor = UIColor.black
        textField.font = UIFont.systemFont(ofSize: 15.0)
        textField.addTarget(self, action: #selector(textFieldDidChangeText(textField:)), for: UIControlEvents.editingChanged)
        self.addSubview(textField)
        
        showView.frame = CGRect(x: 0, y: 0.2*bounds.height, width: bounds.width, height: 0.2*bounds.height)
        showView.isUserInteractionEnabled = false
        showView.textColor = UIColor.blue
        showView.font = UIFont.systemFont(ofSize: 9.0)
        showView.alpha = 0.0
        self.addSubview(showView)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    //MARK: UITextFieldDelegate
    
    func textFieldDidChangeText(textField:UITextField) {
        let text = NSString(string: textField.text!)
        if text.length > 0 {
            showShowView()
        }else{
            removeShowView()
        }
    }
    
    func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
        self.showView.textColor = UIColor.blue
        return true
    }
    
    func textFieldDidBeginEditing(_ textField: UITextField){
        
    }
    
    func textFieldShouldEndEditing(_ textField: UITextField) -> Bool{
        return true
    }
    
    func textFieldDidEndEditing(_ textField: UITextField){
        let text = NSString(string: textField.text!)
        if (text.length > 0) {
            self.showView.textColor = UIColor.darkGray
        }
    }
    
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }
    
    //MARK: CUSTEMMETHODS
    
    func removeShowView() {
        UIView.animate(withDuration: 0.5, animations: {
            self.showView.alpha = 0.0
            self.showView.frame = CGRect(x: 0, y: 0.2 * self.bounds.height, width: self.bounds.width, height: 0.2 * self.bounds.height)
        }, completion: { (End) in
            self.showView.textColor = UIColor.blue
        })
    }
    
    func showShowView() {
        UIView.animate(withDuration: 0.2) {
            self.showView.alpha = 1.0
            self.showView.frame = CGRect(x: 0, y: 0, width: self.bounds.width, height: 0.2 * self.bounds.height)
        }
    }
}