存储 UITextView 字符串/文本数据

Question

所以我正在尝试创建一个显示可编辑的大文本视图的视图。在情节提要中，它被编辑为显示文本“在此处记笔记（向下滑动以关闭键盘）：”作为占位符。

我想让它记住用户何时编辑除此之外的文本......所以我使用 != 做了一个 if 语句，该比较器适用于快速比较字符串。我不确定它是否会得到应用商店审核的批准，因为他们推荐 isEqualToString()。

无论如何，下面的代码都是针对该视图的...如果用户从占位符更改了输入的文本，则它不会记住输入的文本。它识别出它已被更改，但是当您返回视图时，它再次显示默认占位符...帮助？

import Foundation
import UIKit

class MessageNotesViewController: UIViewController, UITextViewDelegate {

@IBOutlet weak var messageNotes: UITextView!
@IBOutlet var swiped: UISwipeGestureRecognizer!

var placeholder = "Take your notes here (Swipe Down to dismiss the keyboard): "

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(true)

    messageNotes.delegate = self
    messageNotes.text = placeholder

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

@IBAction func openIn(_ sender: AnyObject) {

    print("Share with Social Media or Copy to Notes")
    //let textToShare = messageNotes.attributedText

       // let objectsToShare = [textToShare]
        //let activityVC = UIActivityViewController(activityItems: objectsToShare, applicationActivities: nil)


    //activityVC.popoverPresentationController?.sourceView = (sender as! UIView)
    //self.present(activityVC, animated: true, completion: nil)


    if let notes = messageNotes.text {
        let avc = UIActivityViewController.init(activityItems: [notes], applicationActivities: nil)

        avc.popoverPresentationController?.barButtonItem = sender as? UIBarButtonItem
        self.present(avc, animated: true) {
            print("completed")
        }
    }
}

func touchesBegan(_ messageNotes: UITextField) -> Bool {
    self.view.endEditing(true)
    return false
}


//let defaults = NSUserDefaults.

override func viewWillDisappear(_ animated: Bool) {
    //PrepareForSegue didn't quite work
    print("View Will Disappear")

    //Testing if the user has entered any text if so preserve entered text
    if messageNotes.text != placeholder {

        //viewDidLoad(typedText)
        print("the user altered the text in some way. \n")

        placeholder = messageNotes.text
        // assigns new placeholder
    }
    else{
        // do something else - if needed
    }
}
}

//Sub class decleration for ActivityForNotesViewController as called in openIn
class ActivityForNotesViewController: UIActivityViewController {

internal func _shouldExcludeActivityType(_ activity: UIActivity) -> Bool {
    let activityTypesToExclude = [
    ]

    if let actType = activity.activityType() {
        if activityTypesToExclude.contains(actType) {
            return true
        }
        else if super.excludedActivityTypes != nil {
            return super.excludedActivityTypes!.contains(actType)
        }
    }
    return false
}
}

尝试实现以下答案时出现一些编译错误。

在 viewWillAppear 函数中，编译器显示“无法调用非函数类型 'UserDefaults' 的值” - 编译器突出显示行 if let newText 行，UserDefaults.standardUserDefaults() 用红色下划线。

 override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(true)

    messageNotes.delegate = self
    messageNotes.text = placeholder

    if let newText = UserDefaults.standardUserDefaults().objectForKey("textKey"){
        if newText.length > 0 {
            messageNotes.text = newText
        }
    }

}

在viewWillDisappear函数中发现同样的编译错误：

override func viewWillDisappear(_ animated: Bool) {
    //Prepare for segue didn't quite work for what I need
    print("View Will Disappear")

    //Testing if the user has entered any text if so preserve entered text
    if messageNotes.text != placeholder {

        //viewDidLoad(typedText)
        print("the user altered the text in some way. \n")

        UserDefaults.standardUserDefaults().setObject(messageNotes.text!, forKey:"textKey")

        // assigns new placeholder
    }
    else{
        // do something else - if needed
    }
}
}

Answer 1

您需要将更改保存在某处，我建议使用 UserDefaults，这是保存用户偏好和其他小块数据的好方法。

我会在 viewWillDisappear 中替换它：

placeholder = messageNotes.text

与

UserDefaults.standardUserDefaults().set(messageNotes.text!, forKey:"textKey")

在viewWillAppear 我要补充：

messageNotes.text = placeholder
if let newText = UserDefaults.standardUserDefaults().object("textKey"){
    if newText.length > 0 {
        messageNotes.text = newText as! String
    }
}