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."
Related
I have a UITableView inside of a scrollview. I load the datasource from internet content in the background, then call "reloadData". But, it loads EVERY cell. As far as I know, it is supposed to load the cells as they appear onscreen. What is going on?
I guess it happens because a UIScrollView itself does not take care of figuring out which subviews to be shown or not, thats up to a subclass or a delegate.
From: http://developer.apple.com/library/ios/#documentation/uikit/reference/UIScrollView_Class/Reference/UIScrollView.html
The object that manages the drawing of content displayed in a scroll view should tile the content’s subviews so that no view exceeds the size of the screen. As users scroll in the scroll view, this object should add and remove subviews as necessary.
And if you add a table view inside a scroll view I think the table view will load as many cells as needed to draw its bounds without knowing which parts of it that really is on the screen.
I have tableview that scroll vertically. My question is when first this view is loaded, horizontal scrollbar appears at the bottom of tableview and disappears. It only happens when the view loads at the first time. I wonder why this is happening.
I'd hazard a guess that you accidentally checked the “Horizontal Scrollers” box in the table's properties in Interface Builder. To turn them back off again, either find that (under the “Scroll View” section of the inspector) and uncheck it, or just set the table view's showsHorizontalScrollIndicator property to NO in your controller's -viewDidLoad.
I want to put a scroll view inside of the table view cell. I have a number of buttons in one cell of table view and I need to scroll that cell to show the appropriate button.
If you want to use a vertical scroll view then I wouldn't suggest you doing it because, as TechZen wrote, there will be a mess in this case.
If you want the inner scroll view to scroll horizontally then it might be achieved by 2 ways:
Implement a custom table view cell that will include a scroll view inside it.
Add a scroll view as a sub-view to your cell that you will return from tableView:cellForRowAtIndexPath: method.
I suggest you to use the second approach.
There are plenty of examples online. Usually the sub-views are labels or image views, but it is not complicated at all to add a scroll view instead...
I don't think you can do this. It would require nesting of scrollviews which isn't really supported.
Even if it was, it would be very difficult for a user to know which scrollview they were hitting with their pudgy finger. Remember, you don't have the one pixel precision of a mouse on the iPhone. You have an area of at least 15x15 pixels. You don't have a scroll bar but instead just drags anywhere on the screen.
Instead, you should use a master-detail pattern. Selecting the cell in the tableview pushes a detail view which has the scroll view with all the buttons.
Why do you want to do it like this?
I think the best idea is to draw your table view manually above your uiscrollview. I did it, and it works. It just takes more effort and drawing accuracy. But that takes a lot of time. :)
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...
}
How can I create a custom scrollbar for a UITableView?
I want to remove the default one that pops up when tracking begins and that disappears when tracking ends. I want, instead, to have one similar to that in a computer program: (a) it's on the right side of the screen and permanently visible; (b) manually scrolling the bar will scroll the UITableView to the appropriate position; (c) scrolling the UITableView will scroll the scroll bar appropriately (without showing the default one that Apple provides).
The difficulty in (b) and (c) is that, as far as I know, Apple only provides methods to scroll to a particular row/section, but not to scroll to three-fourths of the way down a row. So, for example, if I want to scroll the scroll bar, the UITableView will subsequently only scroll to the top of a row/cell. The method I'm talking about is:
- (void)scrollToRowAtIndexPath:(NSIndexPath *)indexPath atScrollPosition:(UITableViewScrollPosition)scrollPosition animated:(BOOL)animated
Has anyone implemented a custom scroll bar in their UITableView before? Or can someone help me figure out a way to solve the following problems:
scrolling to any point in the UITableView instead of to the start of a cell
removing the default scroll bar and preventing it from appearing
changing the scroll bar image/animation/whatever as the UITableView is scrolled
Thanks!
UITableView inherits from UIScrollView, that means you can use any of the existing functions. In your case
– (void)setContentOffset:(CGPoint)contentOffset animated:(BOOL)animated
should do the job. It moves the table to any position you want.
To disable the existing scroll indicator, use
table.showsVerticalScrollIndicator = NO;
And to add your own, just add your custom view!