[英]How to run code only after all other code is finished?
有点愚蠢的问题,写了一个完整的应用程序,但仍然不知道这一点...现在我有一个“删除帐户按钮”,它删除了所有用户的帖子并执行了返回到登录屏幕的搜索,但似乎并非全部帖子将被删除,因为它会在完成之前执行搜索。
有一种方法只能在删除用户的帖子后才执行segue吗? 与之类似,运行segue LAST。
func actionSheet(actionSheet: UIActionSheet, clickedButtonAtIndex buttonIndex: Int) {
if buttonIndex == 1 { // Post One Pic
//self.performSegueWithIdentifier("postimage1segue", sender: self)
var query = PFQuery(className: "Post")
query.whereKey("userId", equalTo: PFUser.currentUser()!.objectId!)
query.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in
if let objects = objects {
for object in objects {
PFObject.deleteAllInBackground(objects)
}
}
})
var query1 = PFQuery(className: "PrivatePost")
query1.whereKey("userId", equalTo: PFUser.currentUser()!.objectId!)
query1.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in
if let objects = objects {
for object in objects {
PFObject.deleteAllInBackground(objects)
}
}
})
PFUser.currentUser().deleteInBackground()
performSegueWithIdentifier("accountdeletedsegue", sender: self)
}
}
我不确定PFUser是否具有deleteInBackgroundWithBlock:方法,但是您也可以使用Grand Central Dispatch。
这是Obj-C中的示例:
dispatch_group_t group = dispatch_group_create();
dispatch_queue_t bg_queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_group_async(group, bg_queue, ^{
// do something
});
dispatch_group_notify(group, dispatch_get_main_queue(), ^{
//when done do something else on main
});
编辑:Swift GCD组
var downloadGroup = dispatch_group_create()
dispatch_group_enter(group)
// Do something
dispatch_group_leave(group)
dispatch_group_notify(group, GlobalMainQueue) {
//when something is done do something else on main queue
}
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