1. 技术文章
  2. Cannot set searchBar as firstResponder

Cannot set searchBar as firstResponder

由 无人久伴 提交于 2019-12-17 09:09:04

问题


I have a searchBar I'm setting in a tableviewcontroller. i've referenced this similar question UISearchBar cannot become first responder after UITableView did re-appear but am still unable to set it as first responder. In .h file:

@property (strong, nonatomic) UISearchController *searchController;
@property (strong, nonatomic) IBOutlet UISearchBar *searchBar;

In view didload:

self.searchController = [[UISearchController alloc]initWithSearchResultsController:nil];
self.searchController.searchResultsUpdater = self;
self.searchController.dimsBackgroundDuringPresentation = NO;
self.searchController.hidesNavigationBarDuringPresentation = NO;

self.searchController.searchBar.frame = CGRectMake(self.searchController.searchBar.frame.origin.x, self.searchController.searchBar.frame.origin.y, self.searchController.searchBar.frame.size.width, 44.0);
self.tableView.tableHeaderView = self.searchController.searchBar;

And in viewDidAppear:

-(void)viewDidAppear:(BOOL)animated {
  [self.searchController setActive:YES];
  [self.searchController.searchBar becomeFirstResponder];
  [super viewDidAppear:animated];
}

When I segue to the view the searchBar animates, but no keyboard appears.


回答1:


I noticed this issue too. What seems to happen is the call to becomeFirstResponder is done when the searchController is still 'loading'. If you comment out becomeFirstResponder you notice that there is no difference. So we need a way to call becomeFirstResponder after the searchController is 'done' loading.

When I looked at various delegate methods I noticed there is a delegate method:

- (void)didPresentSearchController:(UISearchController *)searchController

This method is called right after the searchController has been presented. Then I make the call to becomeFirstResponder:

- (void)didPresentSearchController:(UISearchController *)searchController
{
    [searchController.searchBar becomeFirstResponder];
}

This fixes the problem. You will notice that when the searchController is loaded, the searchbar now has focus.




回答2:


The solution with - (void)didPresentSearchController:(UISearchController *)searchController did not work, since this delegate method is called only when the user taps on the search bar...

However, this solution did work:

- (void) viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self performSelector:@selector(showKeyboard) withObject:nil afterDelay:0.1];
}

- (void) showKeyboard
{
    [self.searchController.searchBar becomeFirstResponder];
}

Swift 3

delay(0.1) { self.searchController.searchBar.becomeFirstResponder() }

func delay(_ delay: Double, closure: @escaping ()->()) {
    let when = DispatchTime.now() + delay
    DispatchQueue.main.asyncAfter(deadline: when, execute: closure)
}



回答3:


Well, I found the solution that is actually perfectly working for me.

Don't call [self.searchController setActive:YES]; before calling [self.searchController.searchBar becomeFirstResponder];

What's better, don't call [self.searchController setActive:YES]; at all.

Call only [self.searchController.searchBar becomeFirstResponder]; and the keyboard just pops out as it should, without any delay.

It seems to be somewhat like a bug and a lot of people are confirming it. For example, check here: When assigning focus via becomeFirstResponder to UISearchController's UISearchBar, the keyboard does not appear




回答4:


The function searchController.searchBar.becomeFirstResponder() must be called in the main thread and after searchController.active = true in the viewDidLoad method. Here're the full solution. It works on iOS 9.3

override func viewDidAppear(animated: Bool) {
  super.viewDidAppear(animated)
  searchController.active = true
  Async.main {
    self.searchController.searchBar.becomeFirstResponder()
  }
}



回答5:


Swift 4, iOS 11

It works for me

// 1.
override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    resultSearchController.isActive = true
}

// 2. ->> UISearchControllerDelegate
func didPresentSearchController(_ searchController: UISearchController) {

    DispatchQueue.main.async {
        searchController.searchBar.becomeFirstResponder()
    }
}



回答6:


Very similar to other answers, but I had to access the main queue in the ViewDidAppear. The SearchBarController can't be acted upon until the View appears and then can only be done so in the main queue for UI:

searchController.active = true  // doubtful whether this is needed

        dispatch_async(dispatch_get_main_queue(), {
            self.searchController.searchBar.becomeFirstResponder()
        });



回答7:


Easy Swift3 variant:

override func viewDidLoad() {
    super.viewDidLoad()
    navigationItem.titleView = mySearchController.searchBar
    mySearchController.searchResultsUpdater = self
    mySearchController.delegate = self

}

override func viewDidAppear(_ animated: Bool) {
    DispatchQueue.main.async {
        self.mySearchController.isActive = true
    }
}

func presentSearchController(_ searchController: UISearchController) {
    mySearchController.searchBar.becomeFirstResponder()
}

It works ;-)




回答8:


Alternative Approach

This answer looks at a number of issues related to this occurrence and explains the debugging logic used to isolate and determine the specific cause of the problem in my case. Along the way, I share other possibilities that might have worked in other situations and explain why this works in my situation.

tldr; Look at the self.definesPresentationContext = true, the isBeingDismissed, isBeingPresented, canBecomeFirstResponder, and delegate assignment of the SearchController, the Searchbar, SearchResultsUpdater and their delegate methods.

(Source of self.definesPresentationContext solution - See SO answer)

One thing to keep in mind is the context of how the SearchBar is being presented. Embedded in a toolbar, navigation bar, another UIView, as an input or input accessory view. All of which, I've found to have some impact on the timing and internal animation of the search bar as it is being presented or dismissed.

I've attempted all of the solutions presented and none of these worked until I reconsidered how I was trying to use the searchBar. In my case, I was pushing a controller (B) with a search controller from a controller (A) that already had an initial searchcontroller on it. I programmatically embedded each of the search controllers within the titleView of my navigation item when doing a pull refresh.

The answers suggesting adding searchbar.becomeFirstResponder() into the life cycle didn't make sense for my use-case since the view was fully loaded by the time I wanted to insert and display my search bar into the navigationItem. The logic also seemed confusing since the view controller lifecycle methods should already be operating on the main thread. Adding a delay to the presentation also seemed to be an interference with the internal operations of the display and animation used by the system.

I found that calling my function to toggle the insertion worked when I pushed the view controller from controllerA but the keyboard would not display properly when pushed from controllerB. The difference between these two situations was that controllerA was a static tableview controller and controllerB had a tableview controller that I had made searchable by adding its own search controller.

e.g. controllerA with searchbar segues to controllerB with searchbar

Using a number of breakpoints and examining the status of the searchController and the searchbar at different points I was able to determine that the searchController.canBecomeFirstResponder was returning false. I also found that I needed to set the SearchResultsUpdater to self and the delegates on both the searchController and the searchBar.

I finally noted that setting self.definesPresentationContext = true on controllerA was not allowing the keyboard to be displayed when I pushed controllerB onto the navigation stack. My solution was to move the self.definesPresentationContext = true to viewDidAppear on controllerA and in the prepare(for:sender:) method of controllerA I change it to self.definesPresentationContext = false when the destination is controllerB. This resolved the keyboard display issue in my case.

A word on animation ~ I've found that when assigning things to the navigationItem or navigationBar, the system has some built in timing and default animations. I avoid adding custom animation, code in moveToParent methods, or delayed presentations because unexpected behavior occurs in many cases.

Why this solution works

Apple documentation on definesPresentationContext indicates the default behavior and notes some situations where this context adjusts the behavior the controller assigned to manage the keyboard appearance. In my case controllerA was assgined to manage the presentation rather than controllerB, so I just changed that behavior by adjusting this value:

When using the currentContext or overCurrentContext style to present a view controller, this property controls which existing view controller in your view controller hierarchy is actually covered by the new content. When a context-based presentation occurs, UIKit starts at the presenting view controller and walks up the view controller hierarchy. If it finds a view controller whose value for this property is true, it asks that view controller to present the new view controller. If no view controller defines the presentation context, UIKit asks the window’s root view controller to handle the presentation. The default value for this property is false. Some system-provided view controllers, such as UINavigationController, change the default value to true.




回答9:


The answer is to call becomeFirstResponder in viewDidAppear.

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    searchBar?.becomeFirstResponder()
}



回答10:


Swift 5 solution:

override func viewDidLoad() {
        super.viewDidLoad()
        definesPresentationContext = true
        searchController.delegate = self
    }

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    searchController.isActive = true
}

extension ViewController: UISearchControllerDelegate {
 func didPresentSearchController(_ searchController: UISearchController) {
      DispatchQueue.main.async {[weak self] in
          self?.searchController.searchBar.becomeFirstResponder()
       }
  }
}



回答11:


I think there might be a cleaner solution. I found that the keyboard was sort of 'blipping' up and then back down when presented, and calling becomeFirstResponder in didPresentSearchController: was working, but the keyboard was coming in late, and the animation was a bit quirky.

Wrapping my reload data method with a check for presentation made everyone happy:

- (void)updateSearchResultsForSearchController:(UISearchController *)searchController
{
    if (!searchController.isBeingPresented && !searchController.isBeingDismissed) {
        [self.collectionView reloadData];
    }
}

I found this by setting a breakpoint in resignFirstResponder. resignFirstResponder was being called from the reloadData, which in turn was called by updateSearchResultsForSearchController:. It turns out that updateSearchResultsForSearchController: is called during the presentation of the search controller. If you muck with the view hierarchy that the UISearchBar is in during this time, the search controller gets borked. My guess is that the reloadData call was causing the UICollectionReusableView header view to come out and go back into the view hierarchy and forcing the UISearchBar subview to resign first responder.

Another symptom I saw was the the search term was not resetting to the middle of the search bar on cancel, which caused it not to present properly on future clicks.




回答12:


The solution of mixing @edwardmp and @mislovr answers kind of worked for me (keyboard pops out with a slight delay):

- (void)didPresentSearchController:(UISearchController *)searchController {
    [self performSelector:@selector(showKeyboard) withObject:nil afterDelay:0.001];
}

- (void) showKeyboard {
    [self.searchController.searchBar becomeFirstResponder];
}



回答13:


I battled with this for a while but got it working by:

  • Initializing the searchController in viewDidLoad()
  • Setting active = true in viewDidAppear()
    • This triggers didPresentSearchController() in the UISearchControllerDelegate extension.
  • Setting searchBar.becomeFirstResponder() in didPresentSearchController()

Here's the full example, it uses Google Maps Autocomplete.

class myViewController: UIViewController {

    // MARK: Variables

    var resultsViewController: GMSAutocompleteResultsViewController?
    var searchController: UISearchController?
    var resultView: UITextView?

    // MARK: Outlets

    @IBOutlet var myView: UIView!

    // MARK: View Methods

    override func viewDidLoad() {
        super.viewDidLoad()

        resultsViewController = GMSAutocompleteResultsViewController()
        resultsViewController?.delegate = self

        searchController = UISearchController(searchResultsController: resultsViewController)
        searchController?.delegate = self
        searchController?.searchResultsUpdater = resultsViewController

        searchController?.searchBar.prompt = "Search for a Place"
        searchController?.searchBar.placeholder = "place name"
        searchController?.searchBar.text = ""
        searchController?.searchBar.sizeToFit()

        searchController?.searchBar.returnKeyType = .Next
        searchController?.searchBar.setShowsCancelButton(true, animated: false)

        myView.addSubview((searchController?.searchBar)!)
    }

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(true)
        searchController?.active = true
    }

    // MARK: GMSAutocompleteResultsViewControllerDelegate Extension

    extension myViewController: GMSAutocompleteResultsViewControllerDelegate {

        func resultsController(resultsController: GMSAutocompleteResultsViewController,
                       didAutocompleteWithPlace place: GMSPlace) {
            searchController?.active = false
            // Do something with the selected place.
            print("Place name: ", place.name)
            print("Place address: ", place.formattedAddress)
            print("Place attributions: ", place.attributions)
        }

        func resultsController(resultsController: GMSAutocompleteResultsViewController,
                       didFailAutocompleteWithError error: NSError){
            // TODO: handle the error.
            print("Error: ", error.description)
        }

        // Turn the network activity indicator on and off again.
        func didRequestAutocompletePredictionsForResultsController(resultsController: GMSAutocompleteResultsViewController) {
            UIApplication.sharedApplication().networkActivityIndicatorVisible = true
        }

        func didUpdateAutocompletePredictionsForResultsController(resultsController: GMSAutocompleteResultsViewController) {
            UIApplication.sharedApplication().networkActivityIndicatorVisible = false
        }
    }

    extension myViewController: UISearchControllerDelegate {

        func didPresentSearchController(searchController: UISearchController) {
            self.searchController?.searchBar.becomeFirstResponder()
        }
    }
}



回答14:


This is what it worked for me in Swift 4

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    searchController.isActive = true
    DispatchQueue.main.async{
        self.searchController.searchBar.becomeFirstResponder()
    }
}



回答15:


Based on @mislovr's solution, the 0.1 delay was not long enough. Here is my updated code to that answer.

func presentSearchController() {
    searchController.isActive = true

    Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { [weak searchController] timer in
        guard let searchController = searchController else {
            timer.invalidate()
            return
        }

        if searchController.searchBar.canBecomeFirstResponder {
            searchController.searchBar.becomeFirstResponder()
            timer.invalidate()
        }
    }
}



回答16:


To me, there’s a quite big lag when using viewDidAppear. It can be better to use becomeFirstResponder asynchronously in viewDidLoad (tested with iOS 10, Swift 3):

override func viewDidLoad() {
    super.viewDidLoad()

    DispatchQueue.main.async {
        searchController.searchBar.becomeFirstResponder()
    }
}



回答17:


This is what it worked for me in Swift 3.

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    self.perform(#selector(self.showKeyboard), with: nil, afterDelay: 0.1)
}

func showKeyboard() {
    self.searchController.searchBar.becomeFirstResponder()
}



回答18:


In Objective C:

- (void)viewDidLoad {
    [super viewDidLoad];

    // Setup your SearchViewController here...
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    // Will show Cancel button in White colour 
    [[UIBarButtonItem appearanceWhenContainedInInstancesOfClasses:@[[UISearchBar class]]] setTintColor:[UIColor whiteColor]];

    // searchController.active = YES;   // This is not necessary

    // set SearchBar first responder inside Main Queue block
    dispatch_async(dispatch_get_main_queue(), ^{
        [self->searchController.searchBar becomeFirstResponder];
    });
}


来源：https://stackoverflow.com/questions/27951965/cannot-set-searchbar-as-firstresponder

标签
ios
objective-c
uisearchbar
first-responder
uisearchcontroller
易学教程内所有资源均来自网络或用户发布的内容，如有违反法律规定的内容欢迎反馈！
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!