我有一个警告 View ,我正试图在照片 View 上呈现。
照片显示在列表中,可以推送到全屏 View 。
照片 View 正在以编程方式显示。我认为这就是导致问题的原因,因为警报 View 试图在已经呈现的(照片) View 之上呈现另一个 View 。
警报 View 正在尝试显示,但出现此错误:
Warning: Attempt to present <UIAlertController: 0x147d2c6b0> on <LiveDeadApp.ListViewController: 0x147d614c0> which is already presenting (null)
可能有问题的是这一行:
self.present(textPrompt, animated: true, completion: nil)
在主照片 View 上截取屏幕截图时,不会出现警报 View 。但是,当设备的方向发生变化时,照片 View 会返回到列表并显示警报。
iOS 10 中的 Swift 3
谢谢!
这是 ListView 和照片 View 的代码:
import UIKit
import Kingfisher
import SKPhotoBrowser
class ListViewCell: UITableViewCell {
@IBOutlet weak var Cellimage: UIImageView!
@IBOutlet weak var cellVenue: UILabel!
@IBOutlet weak var cellLocation: UILabel!
@IBOutlet weak var cellDate: UILabel!
@IBOutlet weak var aiView: UIActivityIndicatorView!
}
class ListViewController: UITableViewController {
var subcategory:Subcategory!
var objects:[[String:String]] = [[String:String]]()
var images = [SKPhotoProtocol]()
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
}
override func viewDidLoad() {
super.viewDidLoad()
self.tableView.separatorStyle = .none
self.view.backgroundColor = UIColor.black
self.navigationController?.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName: UIColor.white]
navigationController!.navigationBar.barTintColor = UIColor.black
let requireTextInput = "require text input"
// add observer for screen shot
NotificationCenter.default.addObserver(forName: NSNotification.Name.UIApplicationUserDidTakeScreenshot, object: nil, queue: OperationQueue.main, using:
{ notification in
self.definesPresentationContext = true
var inputTextField = UITextField()
let textPrompt = UIAlertController(title: "Test!", message: "Testing!", preferredStyle: .alert)
textPrompt.addAction(UIAlertAction(title: "Continue", style: .default, handler: {
(action) -> Void in
// if the input match the required text
let str = inputTextField.text
if str == requireTextInput {
print("right")
} else {
print("wrong")
}
}))
textPrompt.addTextField(configurationHandler: {(textField: UITextField!) in
textField.placeholder = ""
inputTextField = textField
})
self.present(textPrompt, animated: true, completion: nil)
})
if subcategory != nil {
self.title = subcategory.title
self.objects = subcategory.photos
createLocalPhotos()
self.tableView.reloadData()
}
}
func createLocalPhotos() {
for item in objects {
let photo = SKPhoto.photoWithImageURL(item["url"]!)
photo.shouldCachePhotoURLImage = true
images.append(photo)
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return objects.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell: ListViewCell = tableView.dequeueReusableCell(withIdentifier: "Cell") as! ListViewCell
let item = objects[indexPath.row]
let title = item["title"]
let location = item["location"]
let date = item["date"]
let urlSrt = item["url"]
cell.cellVenue.text = title
cell.cellLocation.text = location
cell.cellDate.text = date
if let url = URL(string: urlSrt!) {
cell.aiView.startAnimating()
cell.Cellimage.kf.setImage(with: url, placeholder: nil, options: nil, progressBlock: nil, completionHandler: { (image, error, cacheType, url) in
cell.aiView.stopAnimating()
})
}
return cell
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let cell = tableView.cellForRow(at: indexPath) as! ListViewCell
if(cell.Cellimage.image != nil ) {
SKPhotoBrowserOptions.displayToolbar = false
SKPhotoBrowserOptions.displayCounterLabel = false
SKPhotoBrowserOptions.displayBackAndForwardButton = false
SKPhotoBrowserOptions.displayAction = false
SKPhotoBrowserOptions.displayDeleteButton = true
SKPhotoBrowserOptions.displayHorizontalScrollIndicator = false
SKPhotoBrowserOptions.displayVerticalScrollIndicator = false
SKPhotoBrowserOptions.displayStatusbar = false
SKPhotoBrowserOptions.disableVerticalSwipe = true
SKPhotoBrowserOptions.bounceAnimation = false
let browser = ExtendedSKPhotoBrowser(originImage: cell.Cellimage.image!, photos: images, animatedFromView: cell)
let btnSize = 80//24 * UIScreen.main.scale
browser.updateCloseButton(UIImage(named: "ic_close_white")!, size: CGSize(width: btnSize, height: btnSize))
browser.updateDeleteButton(UIImage(named: "ic_info_white")!, size: CGSize(width: btnSize, height: btnSize))
browser.initializePageIndex(indexPath.row)
browser.delegate = self
present(browser, animated: true, completion: {})
browser.toggleControls()
}
}
override var prefersStatusBarHidden: Bool {
get {
return true
}
}
var popOverVC:PopUpViewController!
}
extension ListViewController: SKPhotoBrowserDelegate {
func didShowPhotoAtIndex(_ index: Int) {
}
func willDismissAtPageIndex(_ index: Int) {
}
private func willShowActionSheet(photoIndex: Int) {
// do some handle if you need
}
func didDismissAtPageIndex(_ index: Int) {
}
func didDismissActionSheetWithButtonIndex(_ buttonIndex: Int, photoIndex: Int) {
// handle dismissing custom actions
}
func removePhoto(_ browser: SKPhotoBrowser, index: Int, reload: (() -> Void)) {
popOverVC = self.storyboard?.instantiateViewController(withIdentifier: "sbPopUpID") as! PopUpViewController
popOverVC.photoData = objects[index]
}
func viewForPhoto(_ browser: SKPhotoBrowser, index: Int) -> UIView? {
return tableView.cellForRow(at: IndexPath(row: index, section: 0))
}
}
open class ExtendedSKPhotoBrowser: SKPhotoBrowser {
open override var preferredStatusBarStyle: UIStatusBarStyle {
return .lightContent // white statusbar, .default is black
}
open override var prefersStatusBarHidden: Bool {
return true
}
}
最佳答案
问题真的很简单,您正试图在当前呈现的 UIAlertController
上显示另一个 UIAlertController
。
So, how to solve such a case?
您需要获取您在当前 View Controller 中使用的所有
UIAlertController
的列表。您必须检查在当前 View Controller (或其他 View Controller ,如果您正在执行异步请求)中显示警报的逻辑。
当您想要在另一个之上显示一个警报时,您的代码必须像这样。
假设 loadingAlert 当前显示在屏幕上:
self.loadingAlert.dismiss(animated: true, completion: {
let anotherAlert = UIAlertController(title: "New One", message: "The Previous one is dismissed", preferredStyle: .alert)
let okAction = UIAlertAction(title: "OK", style: .default, handler: nil)
anotherAlert.addAction(okAction)
self.present(anotherAlert, animated: true, completion: nil)
})
在下一个出现之前,您必须关闭第一个。我做出这个回答是为了消除没有按钮的警报,以提高效率。
So, what about the alert with action buttons?
It will dismiss automatically when you click one of the action buttons on
UIAlertController
that you created.
但是,如果同时显示两个包含 UIButton
的 UIAlertController
,问题仍然会发生。您需要重新检查每个逻辑,或者您可以在每个操作的处理程序中处理它:
self.connectionErrorAlert.dismiss(animated: true, completion: {
let anotherAlert = UIAlertController(title: "New One", message: "The Previous one is dismissed", preferredStyle: .alert)
let okAction = UIAlertAction(title: "OK", style: .default, handler: {action in
let nextAlert = UIAlertController(title: "New One", message: "The Previous one is dismissed", preferredStyle: .alert)
self.present(nextAlert, animated: true, completion: nil)
})
anotherAlert.addAction(okAction)
self.present(anotherAlert, animated: true, completion: nil)
})
Mike 的回答:
DispatchQueue.main.async(execute: {
if self.presentedViewController == nil {
print("Alert comes up with the intended ViewController")
var inputTextField = UITextField()
let textPrompt = UIAlertController(title: "Test", message: "Testing", preferredStyle: .alert)
textPrompt.addAction(UIAlertAction(title: "Continue", style: .default, handler: {
(action) -> Void in
// if the input matches the required text
let str = inputTextField.text
if str == requireTextInput {
print("right")
} else {
print("wrong")
}
}))
textPrompt.addTextField(configurationHandler: {(textField: UITextField!) in
textField.placeholder = ""
inputTextField = textField
})
weakSelf?.present(textPrompt, animated: true, completion: nil)
} else {
// either the Alert is already presented, or any other view controller
// is active (e.g. a PopOver)
// ...
let thePresentedVC : UIViewController? = self.presentedViewController as UIViewController?
if thePresentedVC != nil {
if let _ : UIAlertController = thePresentedVC as? UIAlertController {
print("Alert not necessary, already on the screen !")
} else {
print("Alert comes up via another presented VC, e.g. a PopOver")
}
}
}
})
感谢@Luke 回答:https://stackoverflow.com/a/30741496/3378606
关于ios - 尝试在已经呈现的 View Controller 上呈现 UIAlertController(空)[Swift],我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41326654/