My question is simple. Is it possible to change the gesture for selecting a cell to be a double-tap instead of the default? If so, what would be the general approach for doing so?
Thanks, in advance.
Regex.
You can use gesture recognizers to capture gesture events.
I've never seen it done in a main interface; I'd be concerned that Apple will reject it as being noncompliant to the HIG.
Related
I found mixed answer to this question whether we should manually remove the gesture recogniser or not. Can anyone provide the better understanding on this?
This says Yes: https://forums.xamarin.com/discussion/16970/gesturerecognizer-should-manually-remove
This says No:Do I need to release a gesture recognizer?
Suggestions please.
If you are NOT talking about using Xamarin then:
No you don't, the answer on the second link you posted is right. The first link is talking about Xamarin, same rules don't apply.
This is how you attach a gesture recognizer.
https://developer.apple.com/documentation/uikit/uiview/1622496-addgesturerecognizer
Under the "Discussion" part you can see this statement:
The view establishes a strong reference to the gesture recognizer.
Whenever you see this kind of statements it can be implied that "This object will keep my added object alive since it will strongly reference it". Thus, once the object disappears my added object will go with it.
Now I have implemented the fling feature in my ios app, but I want to stop the fling when a touch on screen happens, this does not only contain tap gesture, maybe other like long press or pinch, I have a BOOL value to indicate whether a touch happens, so should I add all kinds of gesture recognizers and set to BOOL value as true? Are there any simple solution? Thank you!
There are several methods in UIGestureRecognizerDelegate that will achieve what you want. gestureRecognizerShouldRegognizeSimultaneouslyWithGesture sounds like the best candidate. You will get passed two gesture recognizers. One will be your swipe gesture (the one you want to keep), the other will be the one you want to cancel (tap, long press, pinch) return NO in the correct scenario.
See docs: https://developer.apple.com/documentation/uikit/uigesturerecognizerdelegate
Can anyone clarify the difference between these 2 ways of triggering a function when tapping a view?
1)
myView.addTarget(self, action: #selector(myFunctionToTrigger(_:)), forControlEvents: UIControlEvents.TouchUpInside)
2)
let tapGesture = UITapGestureRecognizer(target: self, action:
#selector(myFunctionToTrigger(_:)))
myView.addGestureRecognizer(tapGesture)
This is 2 completely different ways of implementing user event handling in iOS apps.
1). addTarget() - is method on UIControl class, which is part of Target-Action Mechanism. More about that in documentation.
And you can't addTarget tot any UIView, only to UIControl subclasses.
2). UIGestureRecognizer subclasses is just simply a mechanism to detect and distinguish user gestures on specific view.
Main difference between them that Gesture Recognizers can detect more complex events like swipe or pinch or zoom, but -addTarget is a much more efficient way to detect user activity, also it provides the same level of interface for all UIControls such as UISegmetedControl, UISlider, etc.
Hope that I helped you.
These two method work at two different levels of abstraction:
addTarget:action:forControlEvents is the lower level that provides isolated events. Several of these events must be combined and interpreted to detect more complex gestures like swiping or pinching.
addGestureRecognizer works at a higher level closer to what an app usually needs. It adds specific gesture recoginzer that listen to the low level events, detect gestures and deliver specific information about the gesture.
In the case of a tap, the difference is minor. But when it comes to swiping, pinching and a combination of tapping, swiping, pinching (e.g. in a image viewr or in a map app), one or more gesture recoginzers are the way to go.
Here is the difference
For UITapGestureRecognizer you can add event for specified gestures like UITapGestureRecognizer, UIPanGestureRecognizer... and many other gestures .
Where as For UIView addTarget() you can add target for specified events like UIControlEvents.TouchUpInside.. and many other events.
Pavel's answer is correct, you can only add a target to a UIControlView, which is a subclass of UIView. A UIGestureRecognizer can be added to any UIView.
Codo's answer that a target is lower level than a gesture is wrong, gestures are the lower level touch support. A UIControl uses gestures to make addTarget:action:forControlEvents work.
There are several benefits for addTarget:
It is a build-in function. You don't need to initialize another object to do the same thing.
You can set when to react to the action: "touchUpInside" or "touchDown" (or "valueChanged" for sliders).
You can set the different appearances of the button (e.g. title text, title color, content image, background image, highlight tint) and the button only shows those statuses if addTarget is used.
Besides the benefits above, I think it's more like a coding convention for UIControl elements.
I'm using a UIGestureRecognizer to recognize a single tap, a double tap and a longpress.
What I would like to do is also recognize a longpress, then swipe to either left or right.
Would this be possible given that I'm already consuming a longpress? I'm confused on this one and would appreciate pointers on how to do.
Thanks
Just tried this out myself and it seems as if the UILongPressGestureRecognizer will transition to its end state as soon as the UISwipeGestureRecognizer begins. Just make sure shouldRecognizeSimultaneouslyWithGestureRecognizer: returns YES for this gesture combination.
You'd need to use two gesture recognisers and make sure you track the state of the long press one when you receive a callback to say it's ended, and then do something based on the swipe/pan gesture following it.
is it possible to make custom gestures in iOS such as a zigzag, or a other lines types?
and can one link any action to a gesture. if you know an answer, or a link to an answer or exlanation, please share ... thanks
It is possible to create your own gesture recognizers. You can look at this section of the Event Handling Guide for iOS which gives information as to how you can build your own custom subclass.