Detecting a LongPressGesture has ended in another view controller - ios

I have a LongPressGesture recogniser which when a long press is detected it presents a new segue:
if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {
[self performSegueWithIdentifier:#"showImage" sender:self];
}
The problem being i want the new 'segue' to detect that the gesture had ended and revert back to the previous view controller :
if (gestureRecognizer.state == UIGestureRecognizerStateEnded) {
[self presentViewController:friendViewController animated:YES completion:Nil];
}
I have tried to set up a new gesture recogniser in the new segue but it isn't detected unless the user ends the previous gesture.

You're doing (or trying to do) several things incorrectly. When you segue to the new controller, the long press recognizer's state will go to "failed", so there's nothing more you can do with it. There's no way to add a gesture recognizer to the new controller's view that will accept your previous touch as the beginning of its touch, so that's not going to work. Also, if you want to go back to your previous controller, you shouldn't use presentViewController, that just creates a new instance of friendViewController; it doesn't go back to the old one.
I think the way you need to accomplish your goal, is not to present a new controller, but to add a new view on top of the one with the gesture recognizer. In the example below, I just create a simple view for demonstration purposes, but you could create one in a xib if you need something more complicated.
-(IBAction)handleLongPress:(UILongPressGestureRecognizer *)sender {
if (sender.state == UIGestureRecognizerStateBegan) {
UIView *newView = [[UIView alloc] initWithFrame:self.view.bounds];
newView.backgroundColor = [UIColor redColor];
newView.tag = 10;
[self.view addSubview:newView];
}
if (sender.state == UIGestureRecognizerStateEnded) {
[[self.view viewWithTag:10] removeFromSuperview];
}
}

Related

How to drag down to dismiss a modal with ObjectC

I want to dismiss a modal view with dragging down photo like twitter app's photo views.
I found same issue, but it written in Swift.
I need Object-C version.
You can use UISwipeGestureRecognizer (Down) to achieve the behaviour.
Add gesture to the model view using below code:
UISwipeGestureRecognizer *downGestureRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(downGestureHandler:)];
[gestureRecognizer setDirection:(UISwipeGestureRecognizerDirectionDown)];
[self.view addGestureRecognizer: downGestureRecognizer];
The method to dismiss the model view:
-(void) downGestureHandler:(UISwipeGestureRecognizer *)recognizer {
//Code to dismiss model view with animation
}

SWRevealViewController stop tap gesture when user is in frontView

I am using SWRevealViewController for sliding menu. I have added tap gesture in the front view using:
SWRevealViewController *revealController = [self revealViewController];
[revealController tapGestureRecognizer];
My tap gesture is working. But problem is that my front view has button which require the taps to navigate to other screens. IS there any way to disable the tap gesture when frontView is enabled and enable tap Gesture when menu is pressed?
I think you tried this
create the delegate on your class
#interface xxxViewController () <SWRevealViewControllerDelegate>
on delegate method as
- (void)revealController:(SWRevealViewController *)revealController willMoveToPosition:(FrontViewPosition)position
{
if (position == FrontViewPositionLeftSide) {
self.tapGestureRecognizer.enabled = YES;
// disable your current class action
}
else if (position == FrontViewPositionLeft){
self.tapGestureRecognizer.enabled = NO;
// enable your current class action
}
}
Import SWRevealViewController.h in your slide out menu class. Then in your sliding menu viewWillAppear method put this line-
-(void) viewWillAppear:(BOOL)animated
{
[super viewWillAppear:YES];
self.revealViewController.frontViewController.revealViewController.tapGestureRecognizer.enabled=false;
}
and in viewWillDisappear method put this line-
-(void) viewWillDisappear:(BOOL)animated
{
self.revealViewController.frontViewController.revealViewController.tapGestureRecognizer.enabled=true;
}
In Front view controller add this
SWRevealViewController *objRevealViewController = [self revealViewController];
[self.view addGestureRecognizer:objRevealViewController.tapGestureRecognizer];

UINavigationBar: intercept back button and back swipe gesture

I have a UINavigationBar that intercepts the back button tap that alerts the user if there are unsave changes. This is based on the solution presented in UINavigationController and UINavigationBarDelegate.ShouldPopItem() with MonoTouch using the UINavigationBarDelegate protocol and implementing - (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item;
Now, iOS7 has introduced the swipe-to-go-back gesture, and I'd like to intercept that as well, but can't get it to work with the solutions I've found so far, namely using [self.interactivePopGestureRecognizer addTarget:self action:#selector(handlePopGesture:)]; and
- (void)handlePopGesture:(UIGestureRecognizer *)gesture {
if (gesture.state == UIGestureRecognizerStateEnded) {
[self popViewControllerAnimated:NO];
}
}
While this does pop the views, it leaves the navigation bar buttons in place, so I'm ending up with a back button that leads nowhere, as well as all other navigation button I've added to the nav bar. Any tips?
To intercept the back swipe gesture you can set self as the delegate of the gesture (<UIGestureRecognizerDelegate>) and then return YES or NO from gestureRecognizerShouldBegin based on unsaved changes:
// in viewDidLoad
self.navigationController.interactivePopGestureRecognizer.delegate = self;
// ...
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
if ([gestureRecognizer isKindOfClass:[UIScreenEdgePanGestureRecognizer class]]) {
if (self.dirty) {
// ... alert
return NO;
} else
return YES;
} else
return YES;
}
In the alert you can ask to the user if she want to go back anyway and, in that case, pop the controller in alertView clickedButtonAtIndex:
Hope this is of some help.

SWRevealViewController add gesture to entire front view

Right now I am using SWRevealViewController class in my project.
The basic functionality allows me to swap front view by pressing navigation bar button. But I want to add gesture to entire view.
I can add this code and it works for my button.
[self.startTestButton addGestureRecognizer:self.revealViewController.panGestureRecognizer];
But it just works for the one UI element. So I can't add, for example, other UI element to this gesture.
This code below shows how panGestureRecognizer method has been written:
- (UIPanGestureRecognizer*)panGestureRecognizer
{
if ( _panGestureRecognizer == nil )
{
SWDirectionPanGestureRecognizer *customRecognizer =
[[SWDirectionPanGestureRecognizer alloc] initWithTarget:self action:#selector(_handleRevealGesture:)];
customRecognizer.direction = SWDirectionPanGestureRecognizerHorizontal;
customRecognizer.delegate = self;
_panGestureRecognizer = customRecognizer ;
}
return _panGestureRecognizer;
}
To add the gesture recognizer to the whole view just add it to the whole view instead of just a single button. I'm using SWRevealViewController and my main view is a UITableView so to get the gesture recognizer to work on the whole view I have this in the viewDidLoad method of my UIViewController:
[self.tableView addGestureRecognizer: self.revealViewController.panGestureRecognizer];
So, just add the recognizer to the view you like. For most UIViewContollers this will be self.view.
Obviously if any controls or subviews of the view have their own gesture recognisers, these will take precedence of the one on the top level view, such that the panning will only work in the areas not occupied by those subviews.
//UPD:
Seems my previous solution is a overkill, you just could call getter to get the default behaviour. I.e.
[revealViewController panGestureRecognizer];
// old solution
You could also add SWRevealViewController's panGestureRecognizer to it's own view, for example in a subclass of SWRevealViewController you may have:
- (void)viewDidLoad
{
[super viewDidLoad];
// adds gesture recognizer to the whole thing
[self.view addGestureRecognizer:self.panGestureRecognizer];
}
If you're using a navigation controller and try to add the gesture recognizer to self.view, the gesture won't respond when swiping on the navigation bar. What I did was go into SWReaveal Classes and add a second gesture recognizer. So now I add one recognizer to self.view and one to the navigation bar. Works perfectly. I can share code if you need it but it shouldn't be too hard
To add Gesture on entire front view using SWRevealViewController using storyboard, we have to add
SWRevealViewController *revealController = [self revealViewController];
[revealController panGestureRecognizer];
[revealController tapGestureRecognizer];
in the the FirstViewController of the app. Add Action and Target to the Navigation bar button like
_sidebarButton.target = self.revealViewController;
_sidebarButton.action = #selector(revealToggle:);
// Set the gesture
[self.view addGestureRecognizer:self.revealViewController.panGestureRecognizer];
In the SWRevealViewController.h add following method like
- (UITapGestureRecognizer*)tapGestureRecognizer;
- (BOOL)revealControllerTapGestureShouldBegin:(SWRevealViewController *)revealController;
In the SWRevealViewController.m add
- (UITapGestureRecognizer*)tapGestureRecognizer
{
if ( _tapGestureRecognizer == nil )
{
UITapGestureRecognizer *tapRecognizer =
[[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(_handleTapGesture:)];
tapRecognizer.delegate = self;
[_contentView.frontView addGestureRecognizer:tapRecognizer];
_tapGestureRecognizer = tapRecognizer ;
}
return _tapGestureRecognizer;
}
- (void)_handleTapGesture:(UITapGestureRecognizer *)recognizer
{
NSTimeInterval duration = _toggleAnimationDuration;
[self _setFrontViewPosition:FrontViewPositionLeft withDuration:duration];
}
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
if ( _animationQueue.count == 0 )
{
if ( gestureRecognizer == _panGestureRecognizer )
// return [self _panGestureShouldBegin];
return ( gestureRecognizer == _panGestureRecognizer && _animationQueue.count == 0) ;
if ( gestureRecognizer == _tapGestureRecognizer )
return [self _tapGestureShouldBegin];
}
return NO;
}
In case of xib you can direct use
https://github.com/John-Lluch/SWRevealViewController
On Swift
self.revealViewController().frontViewController.view.addGestureRecognizer(self.revealViewController().panGestureRecognizer())
If you are using a navigation controller for your front view you can add the pan gesture to the nav controller's view like this
[self.navigationController.view addGestureRecognizer: self.revealViewController.panGestureRecognizer];
That way you can also swipe on the navigation bar without altering any classes of the SWReveal controller.

iOS message sent to deallocated instance

I am kinda stumped here. I have a UIModalPresentationFormSheet and I have added a gesture recognizer to handle dismissing the form sheet if the user selects anywhere outside the form sheet. I also have a cancel button in the navbar at the top of the form sheet. When the user selects anywhere outside the formsheet to use the gesture recognizer to dismiss the form sheet, everything works fine. But when they use the cancel button, ignoring the gesture recognizer, once the form sheet is closed I get the error below. I believe its from recognizer being sent to the handleTapBehind method. I dont understand why though because when the view is dismissed, the viewWillAppear should not be called which is allocating the recognizer to a deallocated method (handleTapBehind).
Error:
[CallWebViewViewController handleTapBehind:]: message sent to
deallocated instance 0x21ee5db0
Code:
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
if(UIUserInterfaceIdiomPad == UI_USER_INTERFACE_IDIOM())
{
if(![self.view.window.gestureRecognizers containsObject:recognizer])
{
recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleTapBehind:)];
[recognizer setNumberOfTapsRequired:1];
recognizer.cancelsTouchesInView = NO;
[self.view.window addGestureRecognizer:recognizer];
}
}
}
- (void)handleTapBehind:(UITapGestureRecognizer *)sender {
if (sender.state == UIGestureRecognizerStateEnded)
{
CGPoint location = [sender locationInView:nil];
if (![self.view pointInside:[self.view convertPoint:location fromView:self.view.window] withEvent:nil])
{
[self dismissViewControllerAnimated:YES completion:nil];
[self.view.window removeGestureRecognizer:recognizer];
}
}
}
Add the following to the viewWillDisappear of your viewController:
recognizer.delegate=nil;
Hope this helps.
PS: I don't understand your last sentence:
I dont understand why though because when the view is dismissed, the viewWillAppear should not be called which is allocating the recognizer to a deallocated method (handleTapBehind).
Especially "is allocating the recognizer to a deallocated method" ?

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