import UIKit

class ViewController: UIViewController {

    var lable1: UILabel!
    var lable2: UILabel!
  

    override func viewDidLoad() {
        super.viewDidLoad()
        self.lable1 = UILabel()
        self.lable1.backgroundColor = #colorLiteral(red: 0.8039215803, green: 0.8039215803, blue: 0.8039215803, alpha: 1)  //color literal
        self.lable1.numberOfLines = 1
        self.lable1.text = "Text test"
        //self.lable1.font = UIFont.systemFont(ofSize: 14)
        //self.lable1.font = UIFont.systemFont(ofSize: UIFont.smallSystemFontSize)
        //self.lable1.font = UIFont.italicSystemFont(ofSize: 17)
        //self.lable1.font = UIFont.boldSystemFont(ofSize: 17)
        self.lable1.font = UIFont(name: "Helvetica Meue ", size: 23)
        self.lable1.textColor = UIColor.darkGray
        self.lable1.textAlignment = .center //致中
        self.lable1.lineBreakMode = .byWordWrapping //自動換行方法
        self.lable1.adjustsFontSizeToFitWidth = false //使文字自動適應UILable
        self.lable1.shadowColor = #colorLiteral(red: 0.2549019754, green: 0.2745098174, blue: 0.3019607961, alpha: 1)
        self.lable1.shadowOffset = CGSize(width: 2, height: 2) //陰影偏移量
        self.view.addSubview(lable1) //加上畫面
        
        self.lable2 = UILabel()
        self.lable2.backgroundColor = #colorLiteral(red: 0.2549019754, green: 0.2745098174, blue: 0.3019607961, alpha: 1)
        self.lable2.textColor = #colorLiteral(red: 0.8039215803, green: 0.8039215803, blue: 0.8039215803, alpha: 1)
        self.lable2.numberOfLines = 0
        self.lable2.text = "現時電腦採用 x86 架構，那麼 x86 究竟是什麼大家又清楚嗎？這個字其實是一個「指令集架構」家族的總稱，起源自 1978 年的 Intel 8086 中央處理器，它是一個電腦指令巨集的主流沿用至今，可以說是最成功的電腦架構。它的特點是採用 複雜指令集電腦，Complex Instruction Set Computer 字組，指令數目多而且複雜，電腦需要加以判讀所以效率較低（相對於手機等流動裝置用的的 RISC( reduced instruction set computing) 架構），直到 90 年代技術進步情況才有所改變\n在 8086 之後推出 80286 、80386 、80486 等等處理器，其後再出現 Pentium 、Intel Atom 、 Intel Core i3 、i5 系列都採用 x86 架構，在 2017 年 Qualcomm 其中一個目標就是利用 ARM 處理器(採用 RISC 架構）去模擬出 x86 環境，令到 Qualcomm 處理器都能夠支援 x86 程式。"
        self.view.addSubview(lable2) //加上畫面

    }

    override func viewWillAppear(_ animated: Bool) {
        let frameW = UIScreen.main.bounds.width //找螢幕的寬
        let frameH = UIScreen.main.bounds.height //高
        let gap: CGFloat = 10.0
        //core graphic
        self.lable1.frame = CGRect(x: 0, y: 20, width: frameW, height: 30)
        
        let label1Y = self.lable1.frame.origin.y + self.lable1.frame.height + gap
        let label1W = frameW - gap*2
        let label1H = frameH - label1Y - gap
        self.lable2.frame = CGRect(x: gap, y: label1Y, width: label1W, height: label1H)
    }

}

import UIKit

class ViewController: UIViewController {
    var previousString = ""
    var undoButton: UIButton!
    var doneButton: UIButton!
    var textView: UITextView!
    
    enum ButtonTags: Int {
        case undo = 1, done
    }
    
    var frameW: CGFloat!
    var frameH: CGFloat!
    var gap: CGFloat!
    var textY: CGFloat!
    var textW: CGFloat!
    var textH: CGFloat!
    var keyboardHeight: CGFloat = 0

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        self.initUI()
    }
    
    override func viewWillAppear(_ animated: Bool) {
        self.buttonEnable(false) //
        
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: .UIKeyboardWillShow, object: nil) //通知鍵盤被打開
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(notification:)), name: .UIKeyboardWillHide, object: nil) //通知鍵盤被關閉
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        NotificationCenter.default.removeObserver(self) //取消上面通知，減少記憶體的使用
    }

  //MARK: - fcuntion
    private func initUI() {
        self.view.backgroundColor = UIColor(red: 0.95, green: 0.95, blue: 0.95, alpha: 1.0)
        
        self.frameW = UIScreen.main.bounds.width
        self.frameH = UIScreen.main.bounds.height
        self.gap = 10
        
        let buttonW = (self.frameW - self.gap * 3) / 2
        let buttonH: CGFloat = 30
        self.undoButton = UIButton(frame: CGRect(x: self.gap, y: 20, width: buttonW, height: buttonH))
        self.undoButton.setTitle("UNDO", for: .normal)
        self.undoButton.setTitleColor(UIColor.darkGray, for: .normal)
        self.undoButton.addTarget(self, action: #selector(self.onButtonAction(_:)), for: .touchUpInside)
        self.undoButton.tag = ButtonTags.undo.rawValue
        self.undoButton.layer.cornerRadius = 8.0
        self.undoButton.layer.borderWidth = 1.0
        self.undoButton.layer.borderColor = UIColor.darkGray.cgColor
        self.view.addSubview(self.undoButton)
        
        let undoX = self.gap + buttonW + self.gap
        self.doneButton = UIButton(frame: CGRect(x: undoX, y: 20, width: buttonW, height: buttonH))
        self.doneButton.setTitle("DONE", for: .normal)
        self.doneButton.setTitleColor(UIColor.darkGray, for: .normal)
        self.doneButton.addTarget(self, action: #selector(self.onButtonAction(_:)), for: .touchUpInside)
        self.doneButton.tag = ButtonTags.done.rawValue
        self.doneButton.layer.cornerRadius = 8.0
        self.doneButton.layer.borderWidth = 1.0
        self.doneButton.layer.borderColor = UIColor.darkGray.cgColor
        self.view.addSubview(self.doneButton)
        
        self.textY = 20 + buttonH + self.gap
        self.textW = self.frameW - gap * 2
        self.textH = frameH - textY! - gap //加！可能是nil，解決nil不能減nil的問題
        self.textView = UITextView(frame: CGRect(x: gap, y: textY, width: textW, height: textH))
        self.textView.layer.cornerRadius = 8.0
        self.textView.layer.borderWidth = 1.0
        self.textView.layer.borderColor = UIColor.darkGray.cgColor
        self.textView.textColor = UIColor.darkGray
        self.view.addSubview(textView)
        self.textView.delegate = self
        self.textView.text = """
        如果各位有在關注本網站應該會發從昨天開始就連不上了，找問題找了一天，才發現原先買的Cooler Master 酷媽GX 450W整個不讓我開機了….無奈之下拿其他的Power來支援，更無奈的事發生了…..有7顆硬碟SATA電源線卻不夠，果斷拿起之前主任給的雙Power電源線，加上大4pin轉SATA店的線兩條，伺服器火速重新上線！！
"""
    }
    

    func buttonEnable(_ enable:Bool){
        self.undoButton.isEnabled = enable //上一步的按鈕是否被觸發
    }
    
    func setUI(isKeyboardShown: Bool) {
        let offset = isKeyboardShown ? self.keyboardHeight : 0 //鍵盤有出來就是鍵盤的高度，沒出來就是0
        self.textView.frame.size.height = self.textH - offset
    }
    
    //MARK: - selector
    func onButtonAction(_ sender: UIButton) {
        guard let tag = ButtonTags(rawValue: sender.tag) else { return }
        switch tag {
        case .undo:
            self.textView.text = self.previousString //上一步
        case .done:
            self.view.endEditing(true) //End Editing
        }
    }
    
    func keyboardWillShow(notification: NSNotification) {
        if let infoKey = notification.userInfo?[UIKeyboardFrameEndUserInfoKey], let rectValue = (infoKey as AnyObject).cgRectValue {
            let keyboardFrame = self.view.convert(rectValue, to: nil)
            self.keyboardHeight = keyboardFrame.height
            self.setUI(isKeyboardShown: true)
        } //
        
    }
    
    func keyboardWillHide(notification: NSNotification) {
        self.setUI(isKeyboardShown: false)
    }

}

extension ViewController: UITextViewDelegate {
    
    func textViewDidBeginEditing(_ textView: UITextView) {
        self.previousString = self.textView.text //暫存輸入的文字
    }
    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        print(text)
        self.previousString = self.textView.text
        self.buttonEnable(true) //編輯時按鈕可按
        return true
    }
    func textViewDidEndEditing(_ textView: UITextView) {
        self.buttonEnable(false) //不編輯時按鈕不可按
    }
    
}