I have a subclass of UITableViewController that works as expected. I'd like to capture multitouch events for the whole table to do something with them.
The way I understand it, I should make the tableView of the controller be a subclass of UITableView. In that class I could capture the touchesMoved etc events.
But I also understand that UITableView is a subclass of UIScrollView which hijacks all the touch events so that I never see them.
So, is there some way to still get to those multitouch events for my table? Specifically I'd like to implement something like two-finger pinch/zoom and one-finger horizontal dragging.
Since those touch events are all passed to table cells, perhaps I should do this at table cell level? The only question there is, is this compatible with multitouch? (So that I can aggregate events from different cells as multitouch events and process those...)
EDIT: tried with cells and was able to see some horizontal events. All the vertical events, though, are completely hijacked by the UIScrollView as table scrolls. I wouldn't want to hack this if there's any way at all to make the UIScrollView un-hijack these events...
This solution seems to work fine and feels quite clean. I'll leave the question open for a while, for if someone wants to suggest something else, and then mark this as answer at some point if I won't get anything more.
EDIT: this answer is obsolete, since the modern way to do this, of course, is UIGestureRecognizers.
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I tried implementing the selecting multiple items with a two-finger pan gesture. However, the checkmarks didn't always appear and disappear when tapping edit to start the process, or tapping done when finished.
I later discovered that it works fine when using a UITableViewController after choosing the different controller from cocoa touch menu, instead of the UIViewController and UITableView I was using before.
So my question is: is it correct for me to now assume that these gestures when used in a table are really meant for a dedicated table view controller (with all the extra functionality you only get from it)?
Without any example code, I can't really see what might be going wrong. Have a look at the documentation to see if you are implementing it correctly.
https://developer.apple.com/documentation/uikit/uitableviewdelegate/selecting_multiple_items_with_a_two-finger_pan_gesture
I made a slideview using a uiview and detecting touches to move pages. This slideview is almost like this, except that I made it works like a UITableView.
Now I'm using this to uivews with uiscrollviews. The problem is, "how to distribute touch events to scrollview or slideview?". I had the logic to do. Basically, the uiscrollviews are vertical and slideview is horizontal.
I tried hitTest to keep the touchBegan,Moved,Ended in slideview. When I get a touch movement horizontally, I keep to slideview, when vertically, distribute to uiscrollview. But I cannot figure out how to distribute events to uiscrollview.
Calling [scrollView touchesBegan:touches withEvent:event] doesn't work. I supposed uiscrollview has a different way to work.
If you don't find a clue to your answer, probably, you're wrong.
UIScrollView uses a own way to get touchesBegan, Moved and Ended. Way that I don't, but it's mean if you override touchesBegan to make UIScrollView stops to work, you won't get it. Using hitTest in superview of scroll, you can get the touches before UIScrollView but you can't change the touches target while touches is happening.
After all, there is one way to solve this, ashly, three ways.
1- Simulate touches
I didn't test this, you'll know below. Events come from UIWindow and distributed to subview by - (void)sendEvent:(UIEvent *)event. We don't know how touches target is saved, and change this is completely out of question. But we can use the idea of override superview's hitTest to know what the user will do to make a 'WA' to change the target. To do this, simulate a event of touch ended. Supposed target will be reset. Simulate a event of touch begin again, and this time make sure to let hittest get scrollview.
You can find how simulate events here. The problem is, probably your app will be rejected due using private methods.
2- Make your own UIScrollView
This should be the best or the worst, depending what you want to do. I believe it's painful. And isn't what you want to do right now.
3- Surrender to 'Nest UIScrollView'
To make slideshow of pdf, hq, docs and books, it's the best and painless way. Put a UIScrollView inside another and let them reach an agreement of scrolling. http://developer.apple.com/library/ios/#documentation/WindowsViews/Conceptual/UIScrollView_pg/NestedScrollViews/NestedScrollViews.html
I've decided that I don't want to ever use UIPickerView again... it's completely inflexible in terms of functionality, design, and size (height). It also occasionally gets stuck between rows, and the delay that occurs between letting go of a wheel and when the delegate method is fired indicating that a new row has been selected (because of the "settling in" animation) has caused lots of problems in the context of the apps I've been working on.
That being said, the user-friendly aspects of UIPickerView are good, and I'd like to try to replicate it. I've tried to research different ways that this might be done, but without much success. Does anyone have any ideas as to what would be involved to make something similar from scratch?
I was trying to get a UITableView subclass to behave in such a way that whatever cell was currently in the middle of the table (it would change while dragging, etc.) would change its background colour to something different implying that it was "selected". As soon as the table was dragged such that the "selected" cell was no longer in the middle, the cell would go back to normal and the new middle cell would change colour. So this would be like UIPickerView in a sense that you don't have to tap on a cell; instead you just drag to have one selected by default.
I figured it should have been easy enough to intercept the "touchesMoved" method of UITableView and add some code that looped through all currently viewable cells in the table, checking to see if their frames overlapped the center point of the table, and changing their appearance accordingly (plus sending a notification to other classes as needed to indicate the "selection" change). Unfortunately, I can't get this to work, as the "touchesMoved" method doesn't get called when I drag the table. Am I missing something obvious?
Any ideas or suggestions would be very much appreciated at this point... I made an app that relied heavily on UIPickerView objects, and because of the problems I've run into with them, I'll have to abandon it unless I can figure out a way to make this work.
Thanks very much,
Chris
Remember that a UITableView is a subclass of a UIScrollView, and the UITableViewDelegate gets all the UIScrollViewDelegate method calls too. scrollViewDidScroll: sounds like it would easily fit the bill for knowing when the table view was scrolled.
As for finding which row is in the middle of the view, just use indexPathForRowAtPoint:.
I have an iPhone application which is, in essence, a list. There is a UINavigationBar at the top, and then there is a UITableView which holds the list. I'd like to have an option in some way or another of allowing the user to sort the list in different ways. So, in my mind, I picture having a NavigationItem on the UINavigationBar that, when touched, a little pop up dialogue comes up. You select the "sort" you want, a check mark appears next to it, and the dialogue goes away.
I'm not really sure how to do this. I tried creating a UIView, adding a UIViewController onto it (which held this list of different "sort" parameters (ex. sort alphabetically, sort by date, etc) in a UITableView. But the UITableView isn't responding to any touches, and I'm not sure why.
Does anyone have an idea for using Apples wonderful interface for having an option like this? I can't use a UISegmentedControl below the UINavigationBar, because there are 5 possible options, and I can't fit all that in a single UISegmentedControl.
This sounds like a job for the UIPickerView. You could just slide one up from the bottom of the view whenever that button is pressed. I've done this in the past and it works well.
You won't get a checkmark, but if you want a pop-up I suggest using a UIAlertView.
Have you looked into UIActionSheet at all? https://developer.apple.com/documentation/uikit/uiactionsheet
It seems like it might be a good fit for this approach. The action sheet will be a bit tall since you will have 5-6 buttons in it, but it should get the job done and they are really easy to implement.
The way you are approaching it with displaying another view with its own UITableView in it would work also, but it doesn't seem like the best approach to me. Granted, if you are set on going with that approach, provide us with some code so we can try to figure out why the UITableView isn't responding to touches.
I'm about to start a new iPhone app that requires a certain functionality but I'm not sure if it's doable. I'm willing to research but first I just wanted to know if I should at least consider it or not.
I haven't seen this in an app before (which is my main concern, even though I haven't seen too many apps since I don't own an iPhone), but an example would be the iPhone shortcuts panels: you can hold on an app, and then drag it to another panel, sweeping while still dragging it. But this is the core app, is it possible to reproduce something similar within a normal app?
I only need to be sure it can be done before I start digging, I don't need code examples or anything, but if you have some exact resources that you consider helpful, that would be appreciated.
Thanks!
Yes. If you have your custom UIView subclass instance inside a UIScrollView, your view controller just needs to set the UIScrollView to delay content touches and not allow it to cancel touch events.
[scrollView setCanCancelContentTouches:NO];
[scrollView setDelaysContentTouches:YES];
When the user taps and holds in the custom view, the event goes to that custom view, which can process the touch events to drag an item around, but if the user quickly swipes, it scrolls the view.
The "panel" view that you're referring to appears to be a UIPageControl view — although, perhaps, the specific incarnation of this view that Apple uses for the iPhone's home page may be customized.
Instances of generic UIView views that you might touch-and-drag will receive touch events. By overriding methods in the view, these events can be processed and passed to the page control, in order to tell it to "sweep" between pages.
If I wanted to do what you're asking about, that's how I might approach it. It seems doable to me, in any case.
Start with this: Swip from one view to the next view
Try using a UIButton that tracks the time since the state of the button changed to "highlighted". You may need to do this in order to track the dragging and move the button around:
Observing pinch multi-touch gestures in a UITableView
Check to see if the button starts overlapping one side of the screen while being dragged. If s certain amount of time elapses since the button first started overlapping the edge and then manipulate the UIScrollView so that it switches to the next page on the corresponding side of the screen
You may need to use NSTimer to keep track of how long the button is held down, etc.
In any case there's no reason why this couldn't work.
If UIButton doesn't work then perhaps try a custom subclass of UIControl (which tracks the same touch down actions etc.). If that doesn't work then use the window event intercept thing to track everything.