I have a vertical UIScrollView just wide enough for a single column of buttons. The buttons can be dragged by the user, but when one is being moved I want the other buttons to move up or down out of the way. The only way that I can think of to do this is in the UIPanGestureRecognizer responsible for moving the button, every time its method gets called running a for loop in the subviews, checking the y values. That seems incredibly inefficient, and would require keeping track of which buttons have already moved to prevent moving them more than once. There has to be a better way. Any ideas?
the same functionality has been implemented in this project and in this project also . I hope project code will help you to solve your problem.
Your could use a UITableView with a custom UITableViewCell. Just implement canMoveRowAtIndexPath, moveRowAtIndexPath and targetIndexPathForMoveFromRowAtIndexPath on UITableViewDelegate
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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'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 trying to avoid putting a button in my UITableViewCell subclass so that I don't unnecessarily lag up the scrolling speed.
The button would push another view onto the navigation stack.
I figured since UITableView already has built-in and optimized methods for managing this, that simply limiting the touchable area of my cells would be the easiest and most effective way of achieving my goal.
I really have no idea how I would implement something like this. I have a feeling I would have to override pointInside:withEvent: or hitTest:withEvent:, but I'm not sure how. Managing touchEvents and the UIResponder stuff still escapes me.
So my question is ultimately, in my rootViewController, how would I implement that selecting a row will only work at lets say 220,10,40,40 ?
Thanks!
A UITableViewCell should have a normal selection style(i.e. not UITableViewCellSelectionStyleNone), generally speaking. You shouldn't have buttons on cells that you are reusing an arbitrary number of times.
If you're using a lot of UIButtons in your UITableView, you may want to rethink how your UI is designed.
You can't easily (to my knowledge) change "selectable" parts of a cell - the whole cell must be selectable no matter what(you can set the style to no selection, but you'll still recieve touch updates).
The behavior you're describing sounds like a job for UITableViewCellAccessoryDetailDisclosureButton, actually. If you're going to be pushing another view onto the stack but don't want to do that when the user selects the cell proper, use a detail disclosure button to maximize your consistency with existing UI convention. It's hard to say without more information.
As for doing the work necessary to detect touches in a sub-region, that may be more trouble than it's worth. True, adding subviews to a cell incurs a compositing cost but if you're only talking about one button, and a button whose background you can set to opaque, you'll probably be just fine. The alternative is reinventing the wheel to recreate button behavior in a subregion of the cell and that doesn't sound like functionality that will be much fun to maintain as the SDK matures.
That said, adding views to a cell doesn't incur a compositing cost per se, it's drawing those views that's the trouble. So if you really wanted to go nuts on the optimization, you could create a pre-rendered cell background image that includes the appearance of a button you want and then place a custom, image-free, see-through UIButton instance right over top of it. Nothing to draw, so no additional compositing cost. Worth a shot.
You didn't come here for a premature optimization speech, so I won't bother with one, but I say just do the cell with a normal button for now, make sure you like how the functionality feels to use then optimize toward the end if you're looking at performance that you're not happy with.
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.