Objective-C - Using a subvIew for blocking touches or gestures while validating data

Question

I would like to have a UIView that blocks subviews for responding to gestures. The main purpose is to block the user interface from touches and gestures while data is validated in the server. Once the request has been processed it will removed from the top that blocking UIView.

How can this be accomplished? What I have so far is the following:

@interface TableViewController ()
    @property (weak, nonatomic) IBOutlet UITableView *table;
    @property (strong, nonatomic) IBOutlet UIView *blockingScreen;
    ....
@end

The implementation:

@implementation PlayListViewController

    - (void)viewDidLoad
    {
        [super viewDidLoad];
        _table.dataSource      = self;
        _table.delegate        = self;

        // Blocking screen should take all the screen. 
        // Unfortunately, when it is displayed it gets the table size , ??
        _blockingScreen = [[UIView alloc] initWithFrame:CGRectMake(0,0,
                                         [[UIScreen mainScreen] applicationFrame].size.width,
                                         [[UIScreen mainScreen], applicationFrame].size.height)];

        _blockingScreen.userInteractionEnabled = NO;

        [self loadGestureRecognizer];
    }

    - (void) loadGestureRecognizer
    {
        // Long press gesture recognizer declaration
        UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPressGestureRecognized:)];

        // Swipe gesture recognizer declaration
        UISwipeGestureRecognizer *swipeLeftGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeGestureRecognizer:)];
        swipeLeftGesture.direction = UISwipeGestureRecognizerDirectionLeft;

        // Attach gesture recognizers
        [_songsTable addGestureRecognizer:longPress];
        [_songsTable addGestureRecognizer:swipeLeftGesture];
    }

    // At some point, the gesture recognizer will be invoked
    // In this case when swiping a table row
    - (IBAction)swipeGestureRecognizer:(UISwipeGestureRecognizer *)sender 
    {
        // Do things
        ...

       // Preparing for doing Http request
       // I want to display the blockingScreen on top of all views
       // so no gestures are recognized.
       [_table addSubview:_blockingScreen];
       [_blockingScreen setBackgroundColor:[UIColor blackColor]];
       _blockingScreen.alpha = 0.3;

       // Bring to front
       [_table bringSubviewToFront:_blockingScreen];

       // To avoid gesture recognition I'm forced to do the following
       _table.userInteractionEnabled = NO;
    }
@end

At some point the swipeGestureRecognizer will be invoked by a swipe gesture. That works just fine. The blockingScreen appears to be on top of the table view (deeming just the table) and does not block any gestures.

I'm quite new to objective-c and xcode so explanations, tutorial or external resources are all welcome. I have already read some other answers in SO like How to disable touch input to all views except the top-most view?, Container View Receives Touches Instead of Subview on iPad and tried:

_blockingScreen.userInteractionEnabled = NO;

but also to

_blockingScreen.userInteractionEnabled = YES;

and don't see any difference.

Anyone has any idea?

have you seen answers?? – Dharmbir Singh Mar 19 '15 at 12:55 — Dharmbir Singh, Mar 19 '15 at 12:55

score 1 · Answer 1 · answered Mar 19 '15 at 12:48

This could be accomplished easier by ignoring interaction events while you perform your processing.

[[UIApplication sharedApplication] beginIgnoringInteractionEvents];

// Do all the things

[[UIApplication sharedApplication] endIgnoringInteractionEvents];

gesture recognisers are above views

from docs: "A window delivers touch events to a gesture recognizer before it delivers them to the hit-tested view attached to the gesture recogniser."

so.. the gesture recogniser isn't really disabled by the view.
=> disable it: regconizer.enabled = false

edited Jun 20 '20 at 09:12

Community

1
1

answered Mar 19 '15 at 13:13

Daij-Djan

49,552
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Dharmbir Singh · Answer 3 · 2015-03-19T13:00:24.147

0

You can like this First of all you have to manage isValidated or not and then use like this 1. Solution

-(BOOL) gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
     if (isValidated)
     {
         return YES;  
     }else{
          if(gestureRecognizer.view == songsTable) return NO;
     }
     return YES;
}

Solution You can disable the user's interaction while you calling your server data & you can enable when you get your response from server.

i hope it helps you

edited Mar 19 '15 at 13:00

answered Mar 19 '15 at 12:48

Dharmbir Singh

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66

For solution 2. you mean as @Ell Neal suggested? The point is also about deeming the screen... otherwise the user might be wondering why it is not working. – kitimenpolku Mar 19 '15 at 13:07
@kitimenpolku Please try to use first one option may be helpful. – Dharmbir Singh Mar 19 '15 at 13:27

Objective-C - Using a subvIew for blocking touches or gestures while validating data

3 Answers3

gesture recognisers are above views