I have a view controller that looks like this:
The root view is a scroll view. When the view first loads, it scrolls just fine.
However, I sometimes need to remove one of the buttons at the bottom with code like this:
if (item.url==nil||[item.url isEqualToString:#""]) {
[overdriveButton removeFromSuperview];
}
After doing so, however, the scroll view will no longer scroll. (Those views in the middle of the screen expand, so there's always plenty of content that extends beyond the bottom of the screen).
Note that I am required to use Auto Layout here. My suspicion is that this is part of the problem. Does the removal of the button (and, necessarily, the associated constraints) somehow confuse the scroll view?
Either set UIScrollView's "contentSize" property, or call "sizeToFit" method.
Related
I have a scroll view which contains different ui components such as text fields, labels etc.
The scroll view takes almost the full size of the screen. Logically separated, I want to add/display a button which is not a part of the content of the scroll view.
This leads to the problem that my button doesn't react on my touches. In case, I reduce the size of the scroll view so that the frames don't interfere with the ones from the button, everything works as expected.
I tried to bring the button to the front (view.bringSubviewToFront(infoButton)) but it still doesn't work.
I think you want to implement something like 'Gmail app, a plus button is floating at the bottom right of the screen.
add your scroll view to view and add other elements to scroll view:
view.addSubview(yourScrollView)
yourScrollView.addSubview(yourButton)
yourScrollView.addSubview(yourLabel)
after you finished adding scrollView's sub views it's time to add your button to -> View (not scroll view)
and everything should work fine as you expected
Issue is solved!
It is a matter of how you ad your sub views to the main view. In my case, I added the info button first to the main view followed by adding the scroll view to the main view.
You need to change the order. First you add the scroll view to the main view and then the button.
I am trying to achieve a scrolling over a fixed image, as you can see on the picture.
I thought I should use a scrollview but I didn't quite get it how to use it and what to include into the scrollview, since the image and the button on the bottom should be fixed. In addition, the content should only be scrollable, when the text is to long.
I think the best solution here would be using a UITableView inside a UIViewController.
You can then set up the cells to make it look exactly the way you want.
For instance the first cell would just be the image, the second cell would be your title, the third one would be your menu bar, and so on.
This may be really useful if you plan to present dynamically the elements inside your UIViewController (for example if you need to use a database, you may want to animate the insertion of the rows only if the content has be downloaded already)
So using a UIViewController, you can just add the UITableView to it and set it up using contraints so that it fills the entire view. Then you can just add your button on the top of your table view, as a subview of your UIViewController's view (not as a subclass of your table view otherwise your button would end up scrolling too).
And again here you would need to add a few constraints to your button to make it look alright!
Just try it like this and let me know if you have any difficulties in the implementation :)
It is very complex to explain, To understand you must know good autolayout
To achieve that you need two scrollview and little math :)
Suppose your headerview height is 200
As you know when using autolayout we need following view hierarchy
Your view Hierarchy should be
--> Main View
--> ScrollView
--> Container View
-->Your HeaderView (200)
-->Content View (Equal height to UIView)
--> UIView (Your tabs like button , followbutton)
--> ScrollView 2
--> ContainerView
-->Subviews
Scroll view 1 Will used wo scroll the headerview and second scrollview will used to scroll other content of scrollview (Like Tab and text content as shown in picture )
Content View (Equal height to UIView) will allow your content view to give height of 200 extra to scroll bottom and your second scrollview will scroll to top which will allow to scroll your other content too
https://media.giphy.com/media/a2A4AQeAIkAhO/giphy.gif
is there a possibility to determine if an uiview obj is going to be displayed. imagine: you have 2 uiviews in an uiscrollview. now you are going to switch per gesture from the first view to the second. the first view now is NOT in the viewport. now you are going to go back to the first view. and now I want to be notified that this view is in viewport, or is redisplayed. the same has to be for the second view. I have not found any callback or something like this.
You make sure your UiViewController overrides viewWillAppear: (before it appears this method is called) or viewDidAppear: (after this method is called).
See: http://developer.apple.com/iphone/library/documentation/uikit/reference/UIViewController_Class/Reference/Reference.html#//apple_ref/occ/instm/UIViewController/viewWillAppear:
That depends what you mean by "switch". If one view is just scrolled out of the visible area of the scrollview, but still remains attached as a subview to it, then you may want to check if the bounds of your view overlap those of the scrollviews visible area.
You could do this by using UIScrollView Delegate's scrollViewDidScroll: method to implement a check for overlaps while the user is scrolling.
If however your view is actually removed from the viewstack, then you may want to subclass UIView and implement willMoveToSuperview: to check if the view has been added to the scrollview again.
The "too long; didn't read" version: Is there any way to disable the automatic scrolling behaviour of UIScrollView when telling a UITextField to becomeFirstResponder?
I have a scroll view with paging enabled and several views as subviews, each subview being controlled by its own view controller. Each subview has a UITextField.
The requirement is that when a page is scrolled into view, it's text field should become first responder.
This is fine when using finger swipes to scroll -- I use the scroll view delegate method scrollViewDidEndDecelerating: to know when scrolling stops and a page is in view, I can tell the text field to become first responder.
However, when the scroll view is "autoscrolled", as in when telling the scrollview to scrollRectToVisible:animated:, the scroll view delegate method for deceleration isn't called. I use this method when scrolling newly created pages into view without the user's interation, or when the user taps the UIPageControl.
My solution was to simply set the first responder status of the text field before telling it to scroll into view - but it seems that telling a text field that is in a scroll view to become first responder causes the scroll view to automatically scroll it into view.
I assume this is behaviour used when putting text fields in table view cells (since table views are scroll view subclasses). If you set up a small test app, with a table view, and a text field within a table cell, if the keyboard would obscure the table view cell when it becomes first responder, the table view will automatically scroll it to be visible.
I don't understand, though, why this behaviour occurs in my example, where I'm not using a table view - just a plain scroll view.
I should also mention that my scroll view has vertical scrolling disabled and only scrolls horizontally.
I have tested in another test app that puts text fields as direct subviews of a scrollview (no view controllers or container views) and the same happens. If you tell a text field that is offscreen to become first responder, the scroll view with automatically scroll it for you.
This wouldn't normally be a problem, but it seems to screw up the paging of the scroll view. When I scroll with my finger, each view bounces and is centred properly. But when I scroll a rect to be visible with animation and tell a text field to become first responder, scroll view seems to become conflicted with itself and the view is only scrolled part of the way into view, and isn't centred.
Then, if I touch a view using my finger (not swipe, or even move), the scroll view jumps back to the first page.
My current work around for all this silly auto scrolling behaviour is to use an NSTimer to determine when to update the first responder.
I do the manual scrolling in code using scrollRectToVisible:animated and then after 0.3 seconds, call my method to update the text field to be first responder. (0.3 seconds was trial and error, trying to see which seemed to be the smallest amount of time to allow for the animation but still be long enough not to cause the conflict with the scrollview.
As you can see, this isn't elegant, and is likely to break.
Is there any way to disable the automatic scrolling behaviour of UIScrollView when telling a UITextField to becomeFirstResponder?
Call becomeFirstResponder, then right away, set the contentOffset of the scrollview to its current position..
[textField becomeFirstResponder];
[scrollview setContentOffset:scrollview.contentOffset animated:NO];
Not an answer to your question, but it should fix the problem:
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView
{
// Make the text field first responder...
}
I want to display some kind of indication to guide user to scroll.
Usually when we touch the UITableView scrollbar appears if needed. But I want this scrollbar indication already displayed on my tableview.
How is it possible to do so?
If you have a table view that goes offscreen, you can call
[self.tableView flashScrollIndicators];
and they will flash to show the user that they are there. This is usually put in viewDidAppear.
(If you inherit from UITableViewController then you will have a self.tableView instance variable, if not then substitute another UITableView.)
If you a scroll view's entire contents fit within its view then no scroll bars are displayed; to test this display a table view with only one cell. If the content size is larger than the view's frame then scroll bars will be displayed; only then will [self.tableView flashScrollIndicators]; actually flash scroll indicators.
There's no way to force the scrollbar to appear, short of messing with the internals of UITableView(which you shouldn't do), or redesigning your own table view class.
Per the documentation of UIScrollView's showsVerticalScrollIndicator property: "The indicator is visible while tracking is underway and fades out after tracking."