在两个视图控制器之间将手势识别器实现为Segue

Question

I am building an app called Single Photo. It is part of the "Learn to Code" iBook from Apple. I have built the original app, but now would like to expand on it.

I have added a second View Controller to Main.storyboard, as well as a UIImageView. However, I am not sure how to connect the two View Controllers together. I know that I have to add a segue, but I want to use a swipe gesture (like a photo gallery). It was recommended that I use UIPanGestureRecognizer as an alternative to UISwipeGestureRecognizer.

My confusion is that I am not sure how to implement either UIGestureRecognizer. Do I have to implement it as the segue between the two View Controllers? That would make sense.

tl;dr: How do I implement UIGestureRecognizer as a segue between two View Controllers?

EDIT: When I make some changes, I get the errors seen in the screenshot. {1}: https://i.stack.imgur.com/JpViy.png {1}

Answer 1

I'd be using the Swipe gesture for that; for me it seems the most natural one for changing views with touch?

Whilst I don't know Swift yet sadly, this is how i would do it;

1. Add a gesture recogniser object onto your view using Interface Builder. You'll find it in the list of objects to add (Label, TextField, etc).

2. Add an IBAction method in your ViewController.m and declare it in your .h also like:

- (IBAction)handleSwipe:(UISwipeGestureRecognizer *)recognizer

3. Connect the gesture recogniser in Interface Builder to the IBAction as a 'Sent Action'

4. Make a new Segue by Control-clicking on the first view controller and dragging the blue line to the second view. Give this segue a unique identifier and set the style of segue.

5. Handle the gesture in the IBAction based on direction of swipe and call the segue from here;

   [self performSegueWithIdentifer:@"theSegue" sender:self];

See if that gets you there

Answer 2

It is possible to use a UIPanGestureRecognizer or UISwipeGestureRecognizer to trigger a segue between view controllers, but it's by no means automatic.

I suggest using a UIPageViewController . That is a type of parent view controller that manages a set of child view controllers and lets you page between them, like a photo gallery or iBooks .

There is a demo application built into Xcode called PhotoScroller that will give you the idea. Search on PhotoScroller in the Xcode help system to find it. As I recall it's written in Objective-C, but it will at least give you the idea of how a page view controller works.

Answer 3

tl;dr: How do I implement UIGestureRecognizer as a segue between two View Controllers?

tl;dr: You would write an interactive custom view controller transition animation .

Answer 4

I think that this is a great question that could be answered best if divided into two different sections.

First thing is to understand how to use UIGestureRecognizer so that you can do different things when a user either taps, long presses, rotates, pinches, etc, a certain view. And then, if you want to make a transition between ViewControllers look different than the usual and add a cool effect to it, you will need to learn more about UIViewControllerAnimatedTransitioning , here is a great tutorial for that: APPCODA's Introduction to Custom View Controller Transitions and Animations.

• Let's do an example and try to answer your question:

  1. Let's say you have two ViewControllers, call them MainVC and SecondaryVC and you want to transition from one to the other after the user performs a certain gesture. As you previously mentioned, you can create a segue between them and set an identifier for it (so that you can perform the segue in code later on), you do this by clicking on the segue from your storyboard and going to the Attributes Inspector. For this example let's set the identifier to ToSecondaryVC and do something when the user swipes to the right anywhere in the view.

First thing, you need to initialize a UISwipeGesture object, so let's set the gesture recognizer by adding in the following to ViewDidLoad() of the MainVC class:

    let swipeGesture = UISwipeGestureRecognizer(target: self, action: #selector(MainVC.handleSwipeGesture(_:)))

    // Adding detection for a right swipe
    swipeGesture.direction = .Right
    view.addGestureRecognizer(swipeGesture)

After this you want to create a function in which you will perform the segue (or do anything else really) after the swipeGesture has happened. Like so,

    func handleSwipeGesture(gesture: UISwipeGestureRecognizer) {
        performSegueWithIdentifier("ToSecondaryVC", sender: self)  
    }

I think that should do it for understanding how to use UIGestureRecognizer , and you can work on the other supported gestures by doing something very similar to what we did in this example. Hopefully that helps you a little bit! Best of luck!

Answer 5

Create a segue in storyboard from the initial view controller to your new one. Then click on it and set the identifier to something. Place the first three lines of code in your initial controller's viewDidLoad changing 'MyVC' to your controller's class name. Then put the method in and put the name of the segue you created.

let gesture = UISwipeGestureRecognizer(target: self, action: #selector(MyVC.performChange))
gesture.direction = .right
self.view.addGestureRecognizer(gesture)

func performChange() {
    self.performSegue(withIdentifier: "MySegue", sender: nil)
}