I'm trying to customize the three20 TTPhotoViewController so that the first & last images cannot be dragged.
Example of what I am trying to prevent.
https://plus.google.com/photos/109413514618904450093/albums/5730490807945885537?authkey=CMTi6OfqhLS2NQ
The image shows the currently selected image has been dragged upwards. This behaviour does not occur on the central images only the first & last.
The code responsible for this behaviour is in the TTScrollView. If it was a uiscrollview I would just set bounces to NO.
Can anyone tell me how I can achieve this result?
I think the issue is in TTScrollView:resistPageEdges but my hacking has left me nowhere
TTPhotoViewController delegates TTScrollViewDelegate.
TTScrollViewDelegate has -(void)scrollViewWillBeginDragging:(TTScrollView *).
TTScrollView has (void)cancelTouches.
Therefore, you can write this in your own subclass of TTPhotoViewController.
- (void)scrollViewWillBeginDragging:(TTScrollView *)scrollView {
[scrollView cancelTouches];
}
Every time a user try to drag, it will cancel any active touches and resets everything to an untouched state.
Related
I'm having problems figuring out a way to determine when UICollectionView is/has finished animating.
I currently have a UICollectionView that animates between two subclassed flow layouts using setCollectionViewLayout:animated:
The animation looks great, however, I'm having some undesired behaviour if a user selects a cell during the animation.
I'm looking at ignoring the cell 'selection' by returning NO through the UICollectionViewDelegate method collectionView:shouldSelectItemAtIndexPath: - however - I cannot figure out a reliable test to see if the collection view is currently animating.
Any ideas?
Try checking that there are no animation keys.
BOOL isAnimating = myView.layer.animationKeys.count > 0
I have a UIScrollView, and what I need, is that when the user stops dragging it, the scrollview stops scrolling to.
Sometimes it works, but sometimes, the scroll continues when the pression is released.
I tried a lot of things with the scrollView.tracking, or with delegate methods like scrollViewDidScroll, or scrollViewDidEndDecelerating, etc. But for the moment, I didn't found anything !
I also tried UIPageControl but I need my scroll view to stop every 50 pixel.
Thank you for your time and your help !
You need to impelement this method (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate the decelerate parameter means should scroll view stop immediately or not. Try to use decelerationRate property to set the needed rate.
I've been driving myself mad over this one. It might be one of those things where I need to take a step back and figure out the simplest way to implement this. Can't find anything on this either. I google-fu'd the heck out of this one.
In the Pocket App when you pull down a menu reveals itself just like the searchBar does. In this instance the faux bar when you pull it past its halfway point if you release it shows springs into place. If it is release before the halfway point the bar will snap back and hide. As shown here
In my case I've been trying to replicate this with no luck. In my case I have a UITextView inside of a UIViewController view. I think I have it all wrong.
I can get it to work with a UIScrollView hidden by initiating with it offscreen and then when I press a button the UIScrollView reveals itself. The problem is that this method covers everything so I'll have to resize and relayout a bunch of views. Is this in a UITableView possibly? I want it to be a pull action though and just want to put some TextStrings/Labels in this bar.
Thank you in advance.
Feels like you need a UIScrollView (or UITableView) and to put the menu you want to reveal at the top (in the table view header, for example) and then get the delegate callbacks for scrolling.
UIScrollViewDelegate
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
You might also need to watch for some of the dragging delegate callbacks
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
You can initially hide the menu by setting the content offset to the height of the menu, then catch the delegate callbacks for scrolling and, if the scrolling has reached beyond half the size of the menu set the content offset with animation.
- (void)setContentOffset:(CGPoint)contentOffset animated:(BOOL)animated
If I understand your goal correctly you don't need the scroll view.
What I would do is have an simple UIView containing all the stuff you need and place it outside of the visible area. This will be your pull-down view. Then add an UIPanGestureRecognizer to the view in your UIViewController and use it to track the movement of your finger and update the frame of the pull-down view accordingly. Then in this update method you simply check if the position has passed some threshold and if so you let the pull-down view snap to its final position (using animations of course).
If you are unfamiliar with the UIPanGestureRecognizer there is a really good tutorial here:
http://www.raywenderlich.com/6567/uigesturerecognizer-tutorial-in-ios-5-pinches-pans-and-more
I am working on an app, which actually works like MSPaint (something to draw lines, etc...).
I got a white UIView, basically where the user draws. On top of this UIView I set up a UIImage, which is gray, with a 0,4 alpha. I want this UIImage to be used as a blotting paper. The idea is to disable touch when the user put the palm of his hand on this area, so it's more comfortable to draw (multitouch is disabled, and with this "blotting paper" you won't draw something accidentally with your palm...)
Even if I bring the UIImage to the front, on top of the view, and even if I disable user interactions on this UIImage, it is still possible to draw on the UIView. , behind the UIImage (kind of strange!)
I do not understand what's happening, because, it seems that the image is transparent, and that the UIView "behind" is still active, even if she's overlaid by the UIImage?!
Any help/indication/idea would be much appreciated! Thank you :-)
Have you set the "userInteractionEnabled" property of the UIImage to "NO" ?
You may actually want to do the opposite. When you disable user interaction or touches, the view basically becomes invisible to touches and they are passed on to the next view.
In your case you do want userInteractionEnabled because you want the view to catch those touches.
You have to disable the user interaction on the UIImageView not the UIImage and it should work.
Edit:
Or you could be sneaky and just add an empty view over it. Use the same frame size so it overlaps perfectly and thats it. You'll be able to see everything you need and it's not a subview of it so there will eb no interaction and touches will get registered but won't have any effect. :P
No better ideas unless you post some of your code...
OK, so I managed to do what I wanted to! YAY!
I got 3 different classes :
StrokesViewController (UIViewController)-the view controller
StrokesView (UIView) - the view where the user draws the strokes.
BlottingPaper (UIView) - the blotting paper.
I got a XIB file "linked" to all three.
I created this new class, called "BlottingPaper", typed UIView. the .h and .m file are actually empty (I do import #import < Foundation/Foundation.h >)
User interaction is enable on BlottingPaper.
I do not use the exclusive touch on this class.
On the XIB file, I just put a view on top of StrokesView. I link it to BlottingPaper (modify the alpha as I want, blablabla...)
And that's it! When I put the palm of my hand on it, it doesn't draw anything on the area where my hand is, but I still can draw with my finger on the rest of the StrokesView!
In addition to Dancreek's response, you should be setting buvard.userInteractionEnabled = YES; so that it captures interaction.
You should also set buvard.exclusiveTouch = YES; so that buvard is the only view which will receive touch events.
When you remove buvard you should set buvard.exclusiveTouch = NO; so that other views will regain their ability to receive touches.
I have a UIButton linked up in IB correctly(I believe). The button fires inconsistently, every time I reload the view to show updated info, the button works sometimes and sometimes does not.It gives no errors. I can't find a pattern to when it works and when it doesn't, the same code is run every time I open the view and it still works when it wants. Besides linking it in IB I have also tried to addTarget in ViewDidLoad and remove the IB connection but it still has the same inconsistency,
[_buttonScreen addTarget:self action:#selector(buttonScreenClicked) forControlEvents:UIControlEventTouchUpInside];
If I add NSLog(#"Clicked"); to buttonScreenClicked I see that the method doesn't always get called, what would cause it to do this, I have made sure that I set:
[_buttonScreen setAlpha:0.1];
[_buttonScreen setHidden:NO];
[_buttonScreen setUserInteractionEnabled:YES];
I have no Image, text, or color in the button, but it still works sometimes.
I'm using AFKPageFlipper on the same view but it still had the same problem before I added AFKPageFlipper, so I don't think its that.
If anyone could point me in any direction to start trouble shooting this problem I would appreciate.
Thanks
I just had the same problem and worked it out. The 5 seconds is the clue.
Somewhere you have a gesture recognizer covering the same space as your button. More specifically you have a gesture recognizer that is eating your Taps but not your LongPresses. If you just tap the button the gesture recognizer runs off with your event; Hold your finger down long enough and the gesture recognizer no longer considers it a tap and the event is passed through to your button.
Instrument your Tap gesture recognizer handlers and the problem should pop out at you.
Make sure you don't have any other UIView descendants overlaying the button (like a transparent UIScrollView) as these will intercept the touch events first.
Also make sure that the containing view (the view with the button in) is correctly sized, by default you can place a view outside the bounds of another view and the clipsToBounds is set to false so you will see it but not be able to interact with it.
Things to try:
Do you have any other actions on the button?
Do you have any other UIViews which could possibly be accepting the key presses (above or below, or un-shown)
Also, please check that you have only one UIViewController instance for this screen. Other issues may arrise because of that.
What happens if you dont set the alpha level?
Do you release the object properly in the dealloc only ?
Hope this helps