Cancel out of UISearchBar when user taps on view

问题:

Does anyone know how to cancel (resign First Responder) out of a UISearchBar when you tap below the search text box and above the keyboard? Can anyone help post some code to handle this?

Thanks

回答1:

An alternative idea I got from iphonedevbook, sample code project 04, was to use one big transparent button that lies behind all other controls which does nothing but resign all first responders if tapped. I.e. if the user taps anywhere where there isn't a more important control - which is the intuitive behavior - the search bar and keyboard disappear.

回答2:

Add a tap gesture in the parent view (of the UISearchbar)

[self addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:searchBar action:@selector(resignFirstResponder)]];

回答3:

I accomplished this by using a UITapGestureRecognizer:

UIGestureRecognizer* cancelGesture;

- (void) backgroundTouched:(id)sender {
    [self.view endEditing:YES];
}

#pragma mark - UISearchBarDelegate

-(void)searchBarTextDidBeginEditing:(UISearchBar *)searchBar {
    cancelGesture = [UITapGestureRecognizer new];
    [cancelGesture addTarget:self action:@selector(backgroundTouched:)];
    [self.view addGestureRecognizer:cancelGesture];
}

-(void)searchBarTextDidEndEditing:(UISearchBar *)searchBar {
    if (cancelGesture) {
        [self.view removeGestureRecognizer:cancelGesture];
        [cancelGesture release];
        cancelGesture = nil;
    }
}

The code is a bare, but you can see the intent. When the SearchBar starts editing, you attach a tap gesture recognizer to the view controller's view, and remove it when it stops editing.

There are a couple caveats that you can work around: doing this will make it so if you click anything besides the keyboard or the search bar's text field, the recognizer traps the click -- so if you use the clear, cancel, scope or results button they won't respond correctly.

In my particular scenario, I had a UITableView that was covering the exposed area of the view so I attached the gesture recognizer to it instead of the view controllers main view, isolating the area to which the gesture would respond.

回答4:

I ended up using a hybrid of Hauke's and Beau Scott's approach. There were two problems I ran into using their solutions:

1) If there's anything else on the screen, tapping it won't result in resignFirstResponder being called. For example, if the user taps a button rather than the space around the button, the button will eat the event. Beau Scott's solution addresses this issue, however.

2) Tapping the search bar itself will result in resignFirstResponder getting called. Clearly you don't want the keyboard to disappear when you tap UISearchBar. A small change described below addresses this.

I ended up setting up my view as follows. The parent view has two children - the UISearchBar and a subview which holds the rest of my UI elements. The subview takes up the entire screen below the UISearchBar. Then I used Beau Scott's exact code to add and remove the gesture recognizer, but instead of adding it to self.view I added it to the subview:

IBOutlet UIView *gestureRecognizer;

...

-(void)searchBarTextDidBeginEditing:(UISearchBar *)searchBar {
    cancelGesture = [UITapGestureRecognizer new];
    [cancelGesture addTarget:self action:@selector(backgroundTouch:)];
    [gestureRecognizer addGestureRecognizer:cancelGesture];
}

-(void)searchBarTextDidEndEditing:(UISearchBar *)searchBar {
    if (cancelGesture) {
        [gestureRecognizer removeGestureRecognizer:cancelGesture];
        [cancelGesture release];
        cancelGesture = nil;
    }
}

回答5:

First, you need a reference to the search bar. Let's assume that your controller object has an object reference UISearchBar *theSearchBar, and that you assign it when you create the UISearchBar object.

Next, you need to detect that the containing view has been touched. The view that is touched "knows", but you need get that information to the controller. Sadly, Apple didn't provide a simple way to do this, but it's not that hard either.

My solution is to replace the standard UIView that a UIViewController object normally creates with a UIControl, and then make the UIViewController respond to touch events.

MainController.m

- (void) loadView {
    UIControl *control = [[UIControl alloc] initWithFrame: <desired frame>];
[control addTarget: self action: @selector(touchUpInside) 
             forControlEvents: UIControlEventTouchUpInside];
       // or touch down events, or whatever you like
    self.view = control;
    [control release];
}

- (void) viewDidLoad {
    [super viewDidLoad];
    theSearchBar = [[UISearchBar alloc] initWithFrame: <desired frame>];

    // insert code to finish customizing the search bar

    [self.view addSubview: theSearchBar];
}

- (void) touchUpInside {
    if [theSearchBar isFirstResponder] {
        // grab any data you need from the search bar
        [theSearchBar resignFirstResponder];
    }
}

MainController.h

@interface MainController : UIViewController
{
    UISearchBar *theSearchBar;
}

Clarification:

There is only a single object -- let's call the class MainController -- which is a subclass of UIViewController. All of the methods listed above are implemented in MainController. theSearchBar is declared as a UISearchBar* in the .h file.

Are you defining your view and controller using Interface Builder? If so, I suggest you learn how to NOT use it -- once you get into the kind of tricks we are discussing here, it becomes more of a hindrance than a help -- I don't use it at all, ever.

回答6:

@Gia Dang's answer is the simplest, but I don't subclass the UIView, only the UIViewController, so my call is slightly different. Also, since I don't know the overhead for actually calling resignFirstResponder, I prefer to check first. It's more code, but since all of this is done on the main thread (which can slow down the UI), I'd rather check first.

@implementation MyController : UIViewController {
@private
    UISearchController *_uiSearchController;
}

- (void)viewDidLoad {
    // add tap on view to resign the responder if we're in the middle of typing in the search
    UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(closeKeyboardIfNeeded)];
    [self.view addGestureRecognizer:tapGestureRecognizer];
}

- (void)closeKeyboardIfNeeded {
    if (![_uiSearchController.searchBar isFirstResponder]) {
        return;
    }
    [_uiSearchController.searchBar resignFirstResponder];
}

@end

As for the other answers, be careful about constantly recreating objects. There is always a performance hit, whether it's the creation itself or the garbage collection through ARC, and these things will slow down your main thread. Depending on what you're doing also on the main thread, it may have a significant performance impact.