It's an interesting effect in some magazine. When man swipes, left scrollview and right one will move simultaneously, but with different scoll speed. So sometimes the image in both left and right scrollviews will match together.
Is there any public api to change the scroll speed? I can't find it.
So I try to use scrollViewDidScroll: to control one scrollview from another, but there's alway timedelay between 2 scrollviews. When i move one scrollview, the other will move after about half second. So they aren't simultaneously any more.
Do any one now how to implement it?
Thanks
You cannot change the scroll speed for this. What you can do is make your own animation.
You could just create your own scrollView format and the scroll part, and you'd have to do your own math with whatever timer you are using to make the scrolling look smooth and scroll-like. If you don't believe me, check these out.
1. Change the speed of setContentOffset:animated:?
2. UIScrollView scrolling speed
3. Change the 'Gravity' on a UIScrollView with Paging
4. iPhone UIScrollView Speed Check
the first 3 links are questions similar to yours, the 4th is someone asking how to check the speed of the scroll.
Related
How to edit the minimum distance range that i have to swipe the finger on device to UIScrollView start scrolling? In my case, I am using a horizontal scrolling to change between Views that act like pages. I want to decrease the minimum value because a kind of ugly delay is happening when scrolling (the scroll delays to start). I can provide more information if necessary. Thanks in advance.
The swipe gesture that i mean
I know that I asked a question a few minutes ago, but I want to make a few points clearer before asking for the community's help. I'm new to iOS development, close to finishing my first app. The only thing standing in my way is this UIScrollView. I simply do not understand it, and could use your help.
This is in the detail view controller of a drill-down app with a tab bar. I have approximately 8 fields (for things like phone numbers and such) drawing from a .plist. Obviously, those take up enough room that I could use a little extra real estate. I would guess that it needs to be about the size of two views vertically, but I do not understand how to allocate that sort of space to a UIScrollView. Some tutorials I have read say that you don't even need to define it in the header, which I doubt and do not understand. Additionally, I do not understand how to simply get the app to smoothly scroll up-and down only. Apple's examples have constant move cycles that flip between horizontal pictures.
I doubt it makes very much a difference, but I have an image that is in the background. I'm going to load the view on top of that.
My question is broad, so I don't expect you to take the time to sit down and write out all of the code for me (and I wouldn't ask you to). Just an outline of quick, helpful tips would help me understand how to get this view to load in the context of my project.
Many thanks!
It's fairly simple. Add a UIScrollView to your view. Add your fields and such to the scrollview. In viewDidLoad or somewhere similar, you need to set the contentSize on your scrollview. This is the "virtual" area that will be scrollable. This will generally be larger than the frame of the scrollview. In your case, you indicated it should be roughly double the width.
For instance, if you had a scrollview with a view inside, and you wanted to make sure the entire view is visible via scrolling:
self.scrollView.contentSize = self.contentView.frame.size;
//setting scrollview zoom level
self._scrollview.minimumZoomScale=0.5;
self._scrollview.maximumZoomScale=6.0;
self._scrollview.contentSize=CGSizeMake(320,500 );
you have to outlet scroll view in .h class and #property #synthesis this scroll view.then you can able to scroll up and down,if u want only vertical scrolling ,then u have to go to interface builder and uncheck the horizontal scrolling.
You can set a few settings for your scrollview to limit the scrolling to horizontal or vertical. A few important ones are:
// pseudcode here, start typing "[scrollView " then press escape to get a intelli-sense of all // the things you can set for the scrollview.
// values could be YES/NO or TRUE/FALSE, I can't remember which one but
// I think it's YES/NO. Once you start scrolling, the phone will determine
// which way you're scrolling then lock it to that direction
[scrollView setDirectionalLockEnabled:YES];
// when you slide the view, if enough of the next part of the view is visible,
// the scrollview will snap or bounce the scrollview to fit this new "page".
// think of swiping feature to navigate the iPhone home screens
// to show different "pages" of iphone apps
[scrollView setPagingEnabled:YES];
// as a safe guard, make sure the width of your scrollview fits snuggly with the content
// it is trying to display. If the width is more than necessary to display your table of
// data vertically, sometimes the scrollview will cause the
// horizontal scrolling that you don't want to happen and you get bi-directional scrolling
Just set the content size of UIScrollView after adding all the controls/button/textfields etc. for example you add 10 textfields in UIScrollview then content size of UIScrollView will be
lastTextField.frame.origin.y+lastTextField.frame.size.height+20; 20 is for margin.
That's it let me know if you want to know something more related to your app.
Anyone here happen to know how I might go about making a UIScrollView paging less sensitive?
I am only scrolling left or right, but if I scroll a single pixel in the horizontal direction, the UIScrollView rockets off to the next page. I understand that the paging property stops on multiples of the scrollview's bounds, and that's totally fine. I just don't want this to happen unless it's abundantly clear the user wants to do this.
Can this be done using the native functionality of UIScrollView or will I have to override touch events and code this myself?
Thank you in advance!
I'm trying to have a sort of gesture that will seamlessly switch between a group of images this part I have sorted. The part that is catching me up is the gesture to do so and how I might introduce acceleration.
Basically the user would swipe as normal and after the swipe is registered it would change the image displayed and the faster once swiped the faster the image would change ideally it would then keep that speed until the users finger was lifted leaving the possibility to just scroll repeatedly through the images.
Any direction someone could give me would be great.
Thanks.
Assuming you would be using a UIScrollView for this, setting the scrollView.decelerationRate property would allow you to manipulate the deceleration rate/scroll speed. To calculate the "swipe speed", take a look here: Detecting Special touch on the iphone for some pointers.
I would like to be able to build a scroll view capable of scrolling an unbounded (infinite) distance (this is question number one, how to do this with the contentSize property). The reason for this is so that I can implement a scrolling calendar view, which the user can use to scroll through time along a single axis.
Now, I need to put a view/s in there to mark the dates as they scroll by. My second question is how to implement a view like this in a scroll view. I could have a long view, 3 or 4 times wider than the scrollview frame and just reposition and update that every time the scrolling stops, faking a continuous bar. Any other ideas?
Thanks!
I know it's been a while since you posted this question, but just for future reference:
At WWDC 2011, Apple gave a great presentation called "Session 104 - Advanced Scroll View Techniques". The video can be seen from developer.apple.com or from iTunes.
The main concept:
1 - Start off with a subview that is larger than your scrollView's bounds.
2 - In -layoutSubViews from the scrollView, you check whether the contentOffset in the direction you want to scroll infinitely is past some threshold that you specify (this doesn't have to be any specific value, it could be 1 point in the extreme).
3 - If this is the case, you reset the contentOffset to zero, and you adjust the subview's frame by the same amount.
These last two steps happen within the same run loop cycle, hence the transition will not be visible. Beware that the scrollBar will jump, though. But as your scrollView is infinite, there is no visual feedback the scrollBars could give, anyway, so you'd better hide them when you've finished implementing this.
Not sure it can be... You could try CGSizeZero
http://developer.apple.com/library/ios/#documentation/uikit/reference/UIScrollView_Class/Reference/UIScrollView.html#//apple_ref/occ/instp/UIScrollView/contentSize
contentSize
The size of the content view. #property(nonatomic) CGSize contentSize Discussion
The unit of size is points. The default size is CGSizeZero.
The real question is do you truely want "infinate" or do you want mostly infinate and just make the view ungodly large? Or do you want auto-resizing.
Also a continuous bar for an infinite scrollview? The bar would never move as it wouldn't get any closer to the beginning or the end... You could make a bar that dragging to the right would go into the future and dragging it to the left would go back and then just always reposition it in the center.... Other then that I dunno what would make sense here.
Looping UIScrollView Horizontally sounds like the same sort of problem, hopefully my comments there might give you some ideas as well.
Making an 'infinite' scrollview doesn't work - the memory requirements get way too large. The best way to do it is fake it.
3 screen scrollview:
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| | | |
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Make a scrollview that is 3 times as large as one screen, then when the user finishes scrolling to the next third of the scrollview, move the scroll position back to the center third and scoot the content over to the left. This happens so fast that there is no visible feedback to the user that the scrollview & content was just recentered.
Similarly, when the user scrolls back to the first third, change the scroll position to the center third and move all the content to the right.
For memory management, you should only load as much content as will fit onto those three screens. When you scroll to the next third, you'll reposition, and load the next screen of content.