ios - 无法在 UILabel 中显示我的文本
<p><p>我不知道为什么我不能在我的 UILabel 中打印我的“pocetDatabaze3”。</p>
<p>这是我的代码:</p>
<pre><code>@IBOutlet weak var aktualniPocet: UILabel!
var pocetDatabaze2 = 0
var pocetDatabaze3 = "dfh"
override func viewDidLoad() {
super.viewDidLoad()
if let url = NSURL(string: "http://servis.dronysitmp.cz/cteni_baterie.php") {
let task = URLSession.shared.dataTask(with: url as URL, completionHandler: { (data, response, error) -> Void in
//print(data)
if let pocetDatabaze = NSString(data: data!, encoding: String.Encoding.ascii.rawValue){
self.pocetDatabaze2 = Int(pocetDatabaze as String)!
//self.pocetDatabaze3 = String(describing: pocetDatabaze)
}
}
);
task.resume()
}
pocetDatabaze3 = String(pocetDatabaze2 as Int)
aktualniPocet.text = pocetDatabaze3
}
</code></pre>
<p>在 UILabel 中，它显示“0”，但应该是“25”。加载此 View 后，我还有两个操作。当我使用它们时，它会显示正确的值。剩下的就是:</p>
<pre><code>@IBAction func odecteni(_ sender: UIButton) {
pocetDatabaze2 = pocetDatabaze2 - 1
self.pocetDatabaze3 = String(pocetDatabaze2 as Int)
aktualniPocet.text = pocetDatabaze3
}
</code></pre></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>这是一个线程问题。 <code>URLSession</code> 是异步的，所以你必须在 <code>completionHandler</code> 中更新 UI。</p>
<pre><code>let task = URLSession.shared.dataTask(with: url as URL, completionHandler: { (data, response, error) -> Void in
//print(data)
if let pocetDatabaze = NSString(data: data!, encoding: String.Encoding.ascii.rawValue) {
self.pocetDatabaze2 = Int(pocetDatabaze as String)!
self.pocetDatabaze3 = String(pocetDatabaze2 as Int)
DispatchQueue.main.async {
self.aktualniPocet.text = pocetDatabaze3
}
}
})
</code></pre>
<p>您需要调用 <code>DispatchQueue.main</code>，因为您应该在主线程中更新 UI。然后你可以注释掉另外两个调用。</p></p>
<p style="font-size: 20px;">关于ios - 无法在 UILabel 中显示我的文本，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/46075650/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/46075650/
</a>
</p>
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