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[英]Setting the keyWindow rootViewController not working in iOS8
[英]Swift: Setting rootViewController not working?
我正在嘗試啟動一個新的Swift項目。 這是我第一次嘗試以編程方式創建視圖。 但是,它似乎還沒有加載我的控制器? 我看到的只是啟動屏幕,然后將其加載到模擬器時出現黑屏。
這是我的AppDelegate:
import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(application: UIApplication,
didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
NSLog("zrrrzz") // <------------------------------ Prints properly
self.window?.rootViewController = self.rootViewController()
return true
}
private func rootViewController() -> UIViewController {
NSLog("zzz") // <---------------------------------- Does not print ????
return MapViewController.init()
}
}
MapViewController中:
import UIKit
class MapViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
var label = UILabel(frame: CGRectMake(0, 0, 200, 21))
label.center = CGPointMake(160, 284)
label.textAlignment = NSTextAlignment.Center
label.text = "I am a test label"
self.view.backgroundColor = UIColor.whiteColor()
self.view.addSubview(label)
NSLog("heyyyy!!") //<------------------------------ Also doesn't print ??
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
/*
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
}
*/
}
我錯過了一步嗎? 啟動模擬器時,我沒有看到任何警告/錯誤
在該行中:
self.window?.rootViewController = self.rootViewController()
如果window
屬性為nil
,它將不會執行您的self.rootViewController()
調用。 您可以在文檔中閱讀有關通過可選鏈接進行調用的方法的更多信息。
如果嘗試使用代碼創建初始用戶界面,則需要創建一個UIWindow
實例並將其分配給self.window
。 使用情節提要時,此操作將自動為您完成。
免責聲明 :我沒有在幾個版本的iOS中編寫此代碼,因此這可能並不完全正確,但是它將使您朝正確的方向前進:
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
let applicationFrame = UIScreen.mainScreen().applicationFrame
let window = UIWindow(frame: applicationFrame)
window.rootViewController = self.rootViewController()
window.makeKeyAndVisible()
self.window = window
return true
}
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