在 While 循环中更新文本 Swift

Question

我的程序有一个 while 循环，它运行一些代码，生成各种文本语句。问题是 UILabel 只打印系列中的最后一行文本（我的理解是因为它迭代太快了）。如何让标签打印遇到的所有文本，就像在控制台输出中看到的那样？

我查看了这个 link，但该示例似乎与我的情况不符，并且不确定如何实施修复（如果这是正确的）：

class ViewController: UIViewController {

var locationArray = ["Place A", "Place B", "Place C", "Place D"]
var timeStamp = 0
var playerDead = false

@IBOutlet var labelText: UILabel!

override func viewDidLoad() {
super.viewDidLoad()
} //end viewDidLoad

@IBAction func startGame(_ sender: Any) {
var playerOnePosition = locationArray.randomElement()!
var playerTwoPosition = locationArray.randomElement()!

while (playerDead != true) {
    playerOnePosition = locationArray.randomElement()!
    playerTwoPosition = locationArray.randomElement()!
    timeStamp += 1

    if playerOnePosition != playerTwoPosition {
    labelText.text = "\(timeStamp) Player One is at \(playerOnePosition) and Player Two is at \(playerTwoPosition)"
     } //End first if statement

    if playerOnePosition == playerTwoPosition {
    labelText.text = "\(timeStamp) They are in the same place."
    playerDead = true  //Game ends here
    } //End second if statement
 } //End while loop
 } //End function
 } //End class

通常输出的一个例子是“13 他们在同一个地方”，但我希望 UIlabel 打印导致 13 的所有其他 "timestamp" 事件。

Answer 1

您每次都在设置标签的文本，而不是附加到标签上。替换此行：

labelText.text = "\(timeStamp) Player One is at \(playerOnePosition) and Player Two is at \(playerTwoPosition)"

有了这个：

labelText.text += "\(timeStamp) Player One is at \(playerOnePosition) and Player Two is at \(playerTwoPosition)"

并替换此行：

labelText.text = "\(timeStamp) They are in the same place."

有了这个：

labelText.text += "\(timeStamp) They are in the same place."

请注意，唯一的区别是我将您的 + 运算符更改为 += 运算符。

希望对您有所帮助！

Answer 2

如果您想在每次 if 条件为真时添加新的文本行，您需要追加文本并使用换行符，\n

while (playerDead != true) {
//...
    if playerOnePosition != playerTwoPosition {
        labelText.text = 
             (labelText.text ?? "" ) + 
             "\(timeStamp) Player One is at \(playerOnePosition) and Player Two is at \(playerTwoPosition)\n"
    }

    if playerOnePosition == playerTwoPosition {
        labelText.text = (labelText.text ?? "" ) + "\(timeStamp) They are in the same place."
        playerDead = true  
    } 
}

同时让您的标签显示任意行数，将限制设置为 0

labelText.numberOfLines = 0

在 While 循环中更新文本 Swift

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