简单的问题.如果我在一个完成块内 – 例如使用firebase登录facebook …并且登录成功.如果我想从完成块中解除当前视图控制器(登录视图控制器),我是否需要返回主队列才能执行此操作.我假设登录完成块正在后台线程上完成,并且对UI的任何更改(即解雇当前视图控制器)应该在主线程上完成…这里最好的做法是什么……或者我错过了什么？
@IBAction func facebookLoginTapped(sender: AnyObject) {
//
let ref = Firebase(url: "https://XXXX.firebaseio.com")
let facebookLogin = FBSDKLoginManager()
facebookLogin.logInWithReadPermissions(["email"],fromViewController: self,handler: { (facebookResult,facebookError) -> Void in
if facebookError != nil {
print("Facebook login Failed. Error \(facebookError)")
} else if facebookResult.isCancelled {
print("Facebook login was cancelled.")
} else {
//successfully logged in
//get facbook access token
let accesstoken = FBSDKAccesstoken.currentAccesstoken().tokenString
//use access token to authenticate with firebase
ref.authWithOAuthProvider("facebook",token: accesstoken,withCompletionBlock: { error,authData in
if error != nil {
print("Login Failed. \(error)")
} else {
//authData contains
print("Logged in! \(authData)")
//pop loginvc back to uservc - DO I NEED TO GET MAIN THREAD HERE BEFORE disMISSING VIEW CONTROLLER
self.dismissViewControllerAnimated(true,completion: nil)
}
})
}
})
}
解决方法
你应该“弹出”回主线程来做到这一点.它非常简单,只需包裹
self.dismissViewControllerAnimated(true,completion：nil)就像这样……
Swift 2.x
dispatch_async(dispatch_get_main_queue()){
self.dismissViewControllerAnimated(true,completion: nil)
}
Swift 3&斯威夫特4：
dispatchQueue.main.async {
self.dismiss(animated: true,completion: nil)
}