I would like to have objects in my view which can be dragged and dropped.
When they are dropped in a certain area they should disappear and some code should execute.
How are objects made draggable in an iphone app? Is it just a button which can be drag enabled?
How would one detect the position of the draggable object? Would it be as simple as (Psuedo)
if (draggableButton1.xPosition > e.g. && draggableButton1.xPosition < e,g
&& draggableButton1.yPosition > e.g. && draggableButton1.yPosition < e,g) {
do something
}
?
When user touches the object that time following method is called.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
When moved with touched, following method will be called.
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
When user end with touch, the following method will be used
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
The NSSet object contain the UITouch object which contain all information for touches on view, which view, position on screen , previous position and so more. You can check documentation for that.
Start your logic from touchesBegan and change the position of your object in touchesMoved event. then when user drop object, touchesEnded event will be called. Check for position in touchesEnded event and excute your code as you have said.
May this three methods will help...
If said object is an UIView you can get its frame origin and size.
Check Apples MoveMe example: http://developer.apple.com/iphone/library/samplecode/MoveMe/Introduction/Intro.html
Related
I have a UIView of which I want to know when the user is doing:
touchDownInside (to highlight the view)
touchUpInside (to confirm the action)
touchUpOutside (to cancel and reset the hightlight)
what gestureRecognizer can do this for me?
Please go though these four methods also which your view can override to handle the four distinct touch events:
1) finger or fingers touches the screen
-(void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event;
2)finger or fingers move across the screens(this message repeatedly as a finger moves.)
-(void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event;
3)finger or fingers is removed from the screen
-(void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event;
4) a system event,interrupts a touch before it ends
-(void)touchesCancelled:(NSSet*)touches withEvent:(UIEvent*)event;
You can do this implementing the touches methods itself, why do you need gesture recognizer?
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
The above function for touch down.
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
The above function for touch up. And the combination of both for cancel.
I am working on a semi-piano app with a diffrent keyboard-layout then a usual one.
I created the view manually with UIButtons,
My problem was I that I didn't know how to slide from a UIButton to another,
I figured that out with addTarget with the option of withEvent, which gave me the access to the touches.
Now, after I added the target like this:
[C addTarget:self action:#selector(outsideOfKey: forEvent:) forControlEvents:UIControlEventTouchDragOutside|UIControlEventTouchDragInside];
[C addTarget:self action:#selector(keyGetsLeft: forEvent:) forControlEvents:UIControlEventTouchUpOutside | UIControlEventTouchUpInside];
(also for all of the other keys),
I maneged to make them slideable,
outsideOfKey:forEvent: is as follows:
-(void) outsideOfKey:(id)sender forEvent:(UIEvent *)event
{
for(UITouch *t in [event allTouches])
{
CGPoint touchPoint = [t locationInView:window];
if(CGRectContainsPoint(C.frame, touchPoint))
{
C.highlighted = YES;
}
else{
C.highlighted = NO;
}
(Done for all the other keys as well)
I can slide from and into other keys, and when I leave them in keyGetsLeft:forEvent: I have just used the same syntx without the else, and the highlighted became NO.
Up to here it's easy,
But then when I try to do multi-touch, I can slide only one of the touches all around and the others must stay in the same position.
And even more, If I take one of the fingers away all of them are becoming non-highlighted,
I know the reasons to all of that, but I don't know how to fix it and make it to work.
I would probably move away from UIButtons altogether and implement my own custom touch tracking code. See Handling Multitouch Events in the docs. Namely, you will be implementing the following methods:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
I would probably just implement hit areas, which you could setup in IB, with perhaps a custom UIView touch overlay (just a UIView with a custom subclass). This would let you setup the view in IB with images, titles, etc., but do all of your touch tracking in your custom subclass.
I am afraid, bensnider is right. But I'd implement it via GestureRecognizer:
https://developer.apple.com/documentation/uikit/touches_presses_and_gestures/handling_uikit_gestures
https://developer.apple.com/documentation/uikit/uigesturerecognizer
Each key has one TapRecognizer, while a parent view has a SwipeRecognizer to detect slides form one key to another.
Very useful, on Apple Developer Video Archivelogin with development account required:
WWDC2010: Session 120 — Simplifying Touch Event Handling with Gesture Recognizers
WWDC2010: Session 121 — Advanced Gesture Recognition
I'd use one view for all buttons and manually implement touch tracking as bensnider said. Manually drawing backgrounds/titles also is not so difficult.
Heres a link to an open source iOS piano app I made https://github.com/meech-ward/iOSPiano
I used CALayers for the piano keys and I used
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
to detect if the user is currently touching a piano key.
It works really well even with multiple touches.
I'm new to this site and to iOS programming.
I am working on a percussion app. For this I want to know the x and y location of every finger that touches the screen. I thought this was straightforward, but multitouch is making things confusing for me.
Suppose the user has two fingers pressed on the screen and the user presses a third finger on the screen. How do I determine the location of this third finger?
My feeling is that I need to implement touchesBegan
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
To determine the x and y location I have to look at the touch that triggered this call to touchesBegan. But the touches are presented in an unordered set. If the third finger triggered this touchesBegan, then I have three touches in the NSSet. But since the set is unordered, how do I determine the touch that triggered this third call to touchesBegan? If I understand my documentation correctly it could be any of those three touches.
Many thanks in advance
Maybe you can add a simple counter property and increase its value in touchesBegan and decrease in touchesEnd.
Okay, it now turns out I have been mis-interpreting my test-data. If two fingers already touch the device when a third finger touches the device, only one UITouch object is part of the NSSet in the call to touchesBegan, and not three as I seemed to experience. This one UITouch represents the last fingertouch.
The only time when more than one UITouch object is passed to touchesBegan is when in fact multiple fingers begin to touch the device at the same time.
Since, in my case, I need to handle all new touches based on their location, I need to handle all UITouch objects in the NSSet.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
for ( UITouch *touch in touches)
{
CGPoint location = [touch locationInView:self.view];
// Handle finger touch at given location
// ...
}
}
i am rotating circle in iPad.i have inserted swipegesture event.but I want to different operations in touchMoved and swipeEvent.but when I do touch moving , swipw gesture is called, what i have to do , any help please?
swipe:
NSEventTypeSwipe
An event representing a swipe gesture.
Available in Mac OS X v10.6 and later.
Declared in NSEvent.h.
and
touchMoved:
Sent to the receiver when one or more fingers move in the associated view.
(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
so swipe cant be use to code some thing when any thing happens like touches.swipe is use for recognizing touch event.
I don't have an IPhone and don't really want to pay $130 a month for a cell phone. (I leave mine in the car most of the time, sometimes the entire weekend.) But I covet the technology as a mobile computing platform. (Cruel Fate.) One of the things I like about it the most is the multitouch capability.
How does it look from an API standpoint?
Does the OS have "Gestures" that it knows and passes on an event based on what the user did, or is the application required to interpret a list of "touch and release" events?
How many points can it read? 2, 3... unlimited?
Does Mac OS X proper have this capability if you have a "Multitouch" capabible monitor?
You can always take a look at the documentation to get a better idea of what is supported, but the general methods to implement are:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;
When you tap down, touchesBegan is called with the set of touches that just began. To retrieve all touches currently on the screen, retrieve event.allTouches.
Similarily obvious actions occur when a finger moves or is removed from the screen. The touchesCancelled method is mostly used to support the UIScrollView which allows you to tap something inside a scroll view, then drag the scroll view itself rather that interact with the subview, if certain criteria are met (the scroll view would send a touches cancelled message to the subview when it starts scrolling).
There are no built-in gestures you can watch for to speak of, but there are built-in gestures that the system handles, like swiping across a row in a table to delete it, and pinch-zooming on a UIScrollView.