I have a situation - a UIPageViewController that has scrolling direction vertical. All of its pages are the same height as itself. And then inside each page I have a UIScrollView that also has scrolling in vertical direction.
The point of such an architecture is because i have news with some text between which i want to be able to switch with paging effect, but the news text can be bigger than the screen.
Now i got it all working good with one tiny issue. When you scroll the scrollView to the bottom it bounces (if you turn bouncing on) or just stops (if you turn bouncing off). And only after you lift your finger (stop the touches) you are able to switch to the next page in UIPageViewController.
What i would like to see is when you scroll to the bottom of the UIScrollView it automatically starts scrolling the UIPageViewController without you having to lift up your finger.
I expected that to be the natural behaviour. But its not in ios6 only in 7.
https://www.dropbox.com/s/noua5jo5trv5kn1/iOS%20Simulator%20Screen%20shot%20Sep%2029%2C%202013%207.08.03%20PM.png
https://www.dropbox.com/s/m0965bff5h4eq21/iOS%20Simulator%20Screen%20shot%20Sep%2029%2C%202013%207.08.11%20PM.png
implement UIScrollViewDelegate imside your UIViewConroller
something like
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
if (scrollView.contentOffset.y == scrollView.contentSize.height) {
if (self.nextPageNeededHandler) {
self.nextPageNeedeHandler();
}
}
}
and block in your .h file
#property (nonatomic, copy) void (^nextPageNeedeHandler)(void);
set property like
...
__weak MyPageViewController *self_ = self;
nextPageVC.nextPageNeedeHandler = ^{
[self_ goNextPage];
};
...
Related
I have a scrollview where I have added different views (like tutorial).
What I wanted to have is slider with below design where on scroll I will see previous tut on left side and next on right side.
For this what I have added is scrollview with paging enabled and adding UILabel (for now) in for loop. After adding label in scrollview below is what I had.
To see the data on the left & right, what I did is uncheck clip subviews from storyboard.
However what I noticed is I can scroll only in scrollview area and not outside.
Any idea how can I make UILabel make scrolling outside & inside scrollview.
As of now to make it working, what I have done is added swipe gesture on view and making scrolling programmatically. However what I was looking is if I scroll outside scrollview, it should scroll scrollview little too.
Phewww...
Finally I managed to make it done..
What I did is added one more scrollview (dummyScrollView) with full screen width above main scrollview (mainScrollView) (which I am using to show label).
Now I enabled paging for the dummyScrollView too and implement below where I am scrolling my mainScrollView based on the factor calculation for the dummyScrollView
#pragma mark - UIScrollView Delegate
- (void) scrollViewDidScroll:(UIScrollView *)sender
{
float myFactor = 0;
// 44232 is tag for new scrollview
if (sender.tag==44232) {
myFactor = mainScrollView.frame.size.width/duplicateSV.frame.size.width;
myFactor = duplicateSV.contentOffset.x*myFac;
CGRect mCC = CGRectMake(myFactor, 0, mainScrollView.frame.size.width, mainScrollView.frame.size.height);
[mainScrollView scrollRectToVisible:mCC animated:NO]; // NO is very important... YES will not work
}
// 44231 is main scrollview tag where I won't be doing anything...
if (sender.tag==44231) {
}
}
I would like my UIScrollView to naturally glide to endings at certain incremental values, corresponding to every 50 points of width of a horizontally-scrolling UIScrollView To do this, I customed scrollViewWillEndDragging, like so (as recommended, but not described in detail in an answer here Scrolling a horizontal UIScrollView in stepped increments?):
- (void) scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset{
if(fmodf(targetContentOffset->x, 50.0)){
int roundingNumber1 = 50;
CGFloat newOffset = roundingNumber1 * floor(((scrollView.contentOffset.x)/roundingNumber1)+0.5);
targetContentOffset->x = newOffset;
}
}
However, I am not sure this is actually stopping the view at specific increments, and I also notice that the effect is asymmetric. Though my scrolling motions/velocity/etc are the same, scrolling right is much less fluid than scrolling left. Scrolling right stops faster and more abruptly. There's a video here. Why is this behavior asymmetric and how can I change it?
The reason I thin the scrolling is not stopping at increments of 50 is that I also have a UILabel underneath the scroll view that gets updated by other delegate functions to show the offset. The value it shows is rarely close to 50 when the scrolling is done. Is this because the scrolling is not incrementing to values of 50 or because I am not updating at the right times?
Thanks for any advice.
- (void) scrollViewDidScroll:(UIScrollView *)scrollView{
if(abs(self.lastOffset - scrollView.contentOffset.x) > 49){
CGFloat newNumber = scrollView.contentOffset.x;
self.numberProperty.text = [NSString stringWithFormat:#"%.00f", scrollView.contentOffset.x];
self.lastOffset = scrollView.contentOffset.x;
[self.view setNeedsDisplay];
}
}
- (void) scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView{
self.numberProperty.text = [NSString stringWithFormat:#"%.00f", scrollView.contentOffset.x];
}
Rather than implementing these delegate methods, you can set pagingEnabled on your scroll view to true to get this behavior for free. When paging is enabled, the scroll view will automatically snap to the nearest "page" when you end dragging, where the page width is equal to the scroll view's width.
Based on your video, it looks like the items in your scroll view are smaller than the width of the scroll view itself. To use paging, you'll have to do the following:
Make your scroll view have the same width as one of your items (50.0 units in your case).
Set scrollView.clipsToBounds to false so that the scroll view draws subviews outside of its much smaller bounds.
Set scrollView.pagingEnabled to true so that the scroll view scrolls with paging.
At this point, paging will work but you won't be able to drag the scroll view outside of its bounds. To make this work, you'll need to embed the scroll view in a larger view that forwards touch events to it.
Create a "touch forwarding" class and add it to your view.
This class takes all touch events it receives and sends them to its targetView property instead. DJK is a random prefix I made up for the class name.
#interface DJKTouchForwardingView : UIView
/** The view to which touch events should be forwarded. */
#property (weak, nonatomic) UIView *targetView;
#end
#implementation DJKTouchForwardingView
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
UIView *child = nil;
if ((child = [super hitTest:point withEvent:event]) == self) {
return self.targetView;
}
return child;
}
#end
Make the scroll view a subview of the touch forwarding view and assign it to the targetView property.
Your scroll view will now be scrollable within the bounds of the touch forwarding view and will snap to 50 unit pages.
Example:
You have a UIScrollView with scrollEnabled = NO.
After user pans a certain distance, you want the scroll view to start scrolling.
When finger goes down on screen and I disable scrolling, the scroll view is dead until the finger is lifted. Enabling scrolling in middle of a pan doesn't cause it to start.
I suspect it is because UIScrollView will decide to ignore the touch sequence if it was scrollEnabled=NO during its internal touchesBegan:withEvent: (or its private pan gesture recognizer).
How would you trick it into starting to scroll natively (with bounce effect) in the middle of a touch sequence?
Reason: For a simple UIKit based game that requires this mechanic.
Okay, this still needs a little bit of tweaking to handle scrolling again after the first scroll has stopped, but I think the key to what you're trying to achieve is to implement the UIScrollViewDelegate method scrollViewDidScroll:. From here, you can save the starting content offset of the scroll view, and compare the scroll view's current offset to the starting offset added to the y translation of the scroll view's pan gesture recognizer.
The code below successfully doesn't allow scrolling to start until the user has panned at least 100 pts. Like I said, this needs a little tweaking, but should be enough to get you going.
- (void)viewDidLoad
{
[super viewDidLoad];
[self setStartingOffset:CGPointMake(0.0, -1.0)];
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (self.startingOffset.y < 0.0) {
[self setStartingOffset:scrollView.contentOffset];
}else{
static CGFloat min = 100.0;
CGFloat yTranslation = fabs([scrollView.panGestureRecognizer translationInView:scrollView].y);
if (yTranslation < self.startingOffset.y + min) {
[scrollView setContentOffset:self.startingOffset];
}else{
if (self.startingOffset.y >= 0.0) {
[self setStartingOffset:CGPointMake(0.0, -1.0)];
}
}
}
}
I have a UIScrollView that on it I have also created Gesture Recognizers. Tap, Double Tap, two finger tap, etc. On the Scroll View I create several other UIViews. Think of each of these views as Drawing objects. Circle, Squares, buttons, images, etc. Each of the Subviews I can pan, rotate, tap, etc and they all work for the most part.
If the Scaling Scroll View is not at 100% (1-1) then panning the subviews gets a bit sketchy. you can always tap them to get them to Highlight, though panning, rotation, etc is iffy. Typically if I try to pan a selected subview, it pans the scroll view. Sometimes it works, sometimes it does not. Set the zoom to 100%, or turn off the Scrolling (set scale to the same min/max), I can do what Is expected.
Any Suggestions on where to start troubleshooting this?
Not 100% why this works, but this is the code that made the issue disappear. I had to Subclass UIScrollView, override (BOOL)touchesShouldCancelInContentView:(UIView *)view and return NO if the view was anything but the UIView class for the UIScrollView.View
- (BOOL)touchesShouldCancelInContentView:(UIView *)view {
BOOL returnVal = NO;
if ([view isKindOfClass:[IoScreenEditorContentView class]]) {
returnVal = [super touchesShouldCancelInContentView:view];
}
return returnVal;
}
How can I force a UIScrollView in which paging and scrolling are on to only move horizontally left or horizontally both direction(left and right)?
To be clearer, I'd like to allow the user to 'page only horizontally backward(only bounce when the user try to scroll horizontally right)' OR 'horizontally both direction(this is normal action)' at a given moment.
I am wondering that the solution is the subclass of UIScrollView.
Thanks in advance.
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
if ( only bounce.. ){
// is it right?
if (scrollView.contentOffset.y > 60) {
[scrollView setContentOffset:CGPointMake(0, 60)];
}
}
if ( only paing left... ){
How to do this??
}
}
I'd implement the delegate function scrollViewDidScroll: and store the state (scroll state) of the ScrollView. On subsequent calls, compare with the previous state and have it bounce back (by calling ZoomToRect: maybe) if it is in a particular direction that you don't like.