我在UITableView上设置了一个长按手势,呈现一个包含单元格文本的UIAlertController.当UIAlertController被呈现时,我得到这个警告：
Attempt to present <UIAlertController: 0x7fd57384e8e0> on <TaskAppV2.MainTaskView: 0x7fd571701150> which is already presenting (null)
从我的理解,MainTaskView(UITableView)已经呈现一个视图,所以它不应该呈现第二个视图,UIAlertController.所以我从一个类似的问题尝试了this解决方案.它不工作,因为我得到相同的警告.我可以做些什么来解决这个警告？见下面的代码：
func longpressedView(gestureRecognizer: UIGestureRecognizer){
/*Get cell info from where user tapped*/
if (gestureRecognizer.state == UIGestureRecognizerState.Ended) {
var tapLocation: CGPoint = gestureRecognizer.locationInView(self.tableView)
var tappedindexPath: NSIndexPath? = self.tableView.indexPathForRowAtPoint(tapLocation)
if (tappedindexPath != nil) {
var tappedCell: UITableViewCell? = self.tableView.cellForRowAtIndexPath(tappedindexPath!)
println("the cell task name is \(tappedCell!.textLabel!.text!)")
} else {
println("You didn't tap on a cell")
}
}
/*Long press alert*/
let tapAlert = UIAlertController(title: "Long pressed",message: "You just long pressed the long press view",preferredStyle: UIAlertControllerStyle.Alert)
tapAlert.addAction(UIAlertAction(title: "OK",style: .Destructive,handler: nil))
/*
if (self.presentedViewController == nil) {
self.presentViewController(tapAlert,animated: true,completion: nil)
} else {
println("already presenting a view")
} */
self.presentViewController(tapAlert,completion: nil)
println("presented")
}
控制台输出：
presented You didn't tap on a cell 2015-05-19 22:46:35.692 TaskAppV2[60765:3235207] Warning: Attempt to present <UIAlertController: 0x7fc689e05d80> on <TaskAppV2.MainTaskView: 0x7fc689fc33f0> which is already presenting (null) presented
由于某种原因,当长按手势发生时,两条代码都在if语句中执行.提示警报并将文本打印到控制台.这是个问题吗？
编辑：正如Matt所说,我没有我的所有代码在手势识别器测试的范围内.移动这固定我的问题.测试之外的代码正在执行两次,导致UIAlertController呈现两次.
解决方法
For some reason,both pieces of code are executing in the
if
那应该是响了我的闹钟. if和else都应该运行是不可能的.此代码必须运行两次.
那是因为你没有测试手势识别器的状态.长按g.r.发送其动作消息两次.您正在长时间和发布时运行此代码.你需要测试g.r.的状态.所以你不这样做.例：
@IBAction func longpressedView(g: UIGestureRecognizer) {
if g.state == .Began {
// ... do it all here
}
}