I'd like to know a UIWebView's contentOffset, and/or get didScroll type notifications from it. Am I missing something, or is that impossible.
The thing I'm going for is a UI that's half info panel, half UIWebView. When the app finds out that the user wants to see more of the web view, I'd like to reframe with a smaller info panel and larger web view. When user wants to see less, reframe to half and half.
The problem is the interface is pretty much out of button space. If the web view were a scroll view, I could use scroll actions to discern intent. (scroll down means enlarge, scroll above the top means reduce). Any ideas how I can achieve this with a web view?
UIWebView is made up of UIScrollView.
to access the ScrollView you could use either of the two ways :
UIWebView *aWebView; // Initialization code
UIScrollView *aScrollView;
for (UIView *aView in [aWebView subviews]) {
if ([aView isKindOfClass:[UIScrollView class]]) {
aScrollView = (UIScrollView *)aView;
}
}
OR
aScrollView = [[aWebView subviews] objectAtIndex:0];
Option-1 is a safer way to get the UIScrollView instance...
AND....
If you are building your app for iOS5, you could just call..
aScrollView = aWebView.scrollView;
EDIT
If you check UIWebView in detail, you should have noticed that it conforms to UIScrollViewDelegate
If your primary intent is to provide custom gesture-type action on top of the UIWebView, you can try UIGestureRecognizer.
(Do not forget to provide UIGestureRecognizerDelegate's gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer implementation to allow webview own gesture recognizers to work properly)
Related
I am attempting to implement a UIScrollView with a UIPageControl following the guide on this website:
http://www.iosdevnotes.com/2011/03/uiscrollview-paging/
In opposite to the guide, I am implementing this in a storyboard project, and using XCode4.5.2. In addition to the code in the guide, I have added at the beginning of the #interface, and inside the viewDidLoad method in the implementation, I have added scrollView.delegate = self.
With only the code and IB-objects described in the guide added to my app, it doesn't allow me to scroll at all when I test it on my iPhone. The only scrolling i can do is by swiping my finger over the UIPageControl, which makes the "white dot" in the PageControl move one spot towards the direction I was swiping, and with no visible changes in the ScrollView. In the guide we add different colours to the backgrounds of the views in the scrollView -- none of these colours show up at all.
I have tried debugging by putting NSLogs in my code to see what methods are reached by the app. Adding an NSLog (#"View did load"); right after [super viewDidLoad]; in the viewDidLoad method atop the main view controller doesn't output anything to the terminal. Does this mean my app doesn't load up properly?
Thanks in advance!
Do you have multiple pages added to the scrollView? Scrolling is default off if you only have one page worth of content. Ensure that the loadScrollView method is called and also add this:
scrollView.pagingEnabled=YES;
If you are interested I created this class for paging with the scrollview
https://github.com/andrealufino/ALScrollViewPaging
How would one get the contentOffset or similar information about a UIScrollView while the user is still scrolling? For example if I wanted to place an image as a header right above the content of a UIWebView, without the image being part of the WebView's scrollView, but have it update while the user scrolls, not just jumping to the position after they let go. How could I go about doing this?
In iOS 5, the UIWebView has a scrollView property which is the UIScrollView responsible for handling the scrolling. Prior to iOS 5 you can search the UIWebView's subviews property for the subview using [subview isKindOfClass:[UIScrollView class]].
Once you have the UIScrollView, you can then set its delegate property. In the delegate you can then respond to the scrollViewDidScroll: message when the user scrolls, and update the position/contents of your header view.
Added: 29/2/2012 - In order to preserve the UIWebView's functionality, you will need to forward your intercepted UIScrollViewDelegate methods to the UIWebView too. To do this, you can call the UIWebView at the end of all mandatory methods within the protocol and implement something like forwardInvocation: or forwardingTargetForSelector for the optional protocol methods. This will preserve your original UIWebView behavior and allow you to enhance it with your own logic.
Why can't you just put the header as a separate view above the UIWebView? Why does it have to be a subview?
Is the following easy to code?
I have a tableview and when the user selects a cell a detail view is loaded.
I want to allow the user to navigate throughout the items/detail-view representing the items in the tableview by left and right swipes, working in the same way as e.g. the home-screen of the iphone (e.g. while swiping, one page is moving off the screen and the next appears).
I have seen this implemented in the MobileRSS-APP, so it is possible, but I just have a hard-time figuring out the way to do it properly.
Thanks a million in advance! I am still trying to find my feet with cocoa-touch...
This is not a secret, Apple provides the sample code called the PageControl that demonstrates exactly what you want to achieve:
This application primarily demonstrates use of UIScrollView's paging functionality to use horizontal scrolling as a mechanism for navigating between different pages of content.
I implemented it in many of my apps.
The iphone home screen (springboard) works with a scroll view set to paging enabled.
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0,0,self.view.frame.size.width, self.view.frame.size.height)];
[scrollView setPagingEnabled:YES];
Then, lets say there's two pages of apps to swipe through - you set the content size of the scroll view to twice the width of your view:
[scrollView setContentSize:CGSizeMake(self.view.frame.size.width*2, self.view.frame.size.height)];
And thats how that is done. :) I don't know if its the same for the MobileRSS-APP.
Things to bear in mind:
This isn't the default way a table view works. You might get your app rejected by apple. A table view is meant to work by clicking.
You could probably replicate the functionality without using a scroll view using touches methods and the navigation controller. A good tutorial describing how to detect swipes on your view is here: http://www.dosomethinghere.com/2009/07/23/simple-swipe-detection-in-the-iphone-sdk/
In the last method in that tutorial where there is the NSLog("swipe right") you could replace that with [self.navigationController popViewControllerAnimated:YES] which would replicate pressing the "back" button in the navigation bar.
I don't know what you could do for swipe left though..... if you wanted to do this on the table view you'll have to do some complicated maths determining how far the table view has been scrolled. Or you could test for touch events on the cells themselves, but thats something you wil have to look into. :)
I know this has been talked about a lot. I think I've gone thru every question on this site, and still have not been able to get this working.
I'm new to developing but I have a good sense of what's going on with all of my code. I definitely don't have a lot of experience though, this is my first iPhone app.
I'm making a data entry field that is comprised of multiple UITextFields within a UIScrollView. I'll avoid explaining the other details for now, as it seems its a very basic problem. Without a scrollview, the textfields work perfectly. I can touch the textfield and the keyboard or picker view show up appropriately. When I add the textfields to a scrollview, the scrollview works, but then the text fields don't receive my touches.
Here's the key: When 'User Interaction' is ENABLED, the scrollview works but the textfield touches are NOT registered. When 'User Interaction' is DISABLED, the scrollview doesn't work, but the textfield touches ARE registered and the keyboard/picker pops up.
From the other posts I have seen people creating subclasses and overriding the touches in a separate implementation. I've seen people using custom content views (subviews?), I've seen some solutions that are now obsolete since the APIs have changed in newer versions of the SDK, and I am just completely stuck.
I will leave out my code for now, because maybe there is a solution that someone has without requiring my code. If someone needs to see my code, I will put it up. My app is being written in the 3.1.3 SDK.
If anyone has ANY information that could help, it would be so greatly appreciated.
Here is what worked for me in Xcode 4.3.3.
In the storyboard, select your scrollview. Select Attribute Inspector on the right side. Uncheck Delays Content Touches.
It sounds like you're using IB to do a lot of your UI layout. If you take a programmatic approach you could set-up the following view hierarchy which should work.
Your view controller object managing your scroll view and your text fields should have a UIScrollView object and a UIView object (in addition to any UITextField objects you need). In the loadView method of the view controller class, allocate and initalize the UIView object and add your text fields to it as subviews. At the end of the method, allocate and initalize the UIScrollView object then add the UIView to the UIScrollView as a subview.
As an example, if your UIScrollView object were called scrollView and your UIView object called mainView the following lines at the end of the view controller's loadView method would properly set up the scroll view with the main view with the text fields on it:
scrollView = [[UIScrollView alloc] initWithFrame: [[UIScreen mainScreen] bounds] ];
scrollView.backgroundColor = [UIColor whiteColor];
scrollView.contentSize = mainView.frame.size;
[scrollView addSubview: mainView];
self.view = scrollView;
You may need to enable / disable user interaction for both the scroll view and text fields as necessary.
If possible you might best using different touch mechanisms for each process (scrolling and textfield input).
Maybe you can check the time differential between touch start and end such that you can detect the difference between a drag (scroll) and a tap (text input).
Having said that if you propagate the touches up from the textfields to the scrollview you should be fine. One thing I use is:
[myObject addTarget:self action:#selector(itemTouchedUpInside:) forControlEvents:UIControlEventTouchUpInside];
which passes the object touched so you can identify it and act accordingly.
I have a horizontal UIScrollView that contains UIButtons (though it could be any object). I would like to only download images for these buttons as the user scrolls and they are seen. I would also like an activityindicator running on each button while the images are downloading. Here's what I've tried with results:
Check content offset of uiscrollview and download images for visible buttons. Problem: issues getting activity view shown within subclassed UIButton and not desired usability since images are only downloaded once scrolling stops.
Add subviews (not buttons) to the UIScrollview hoping to use the view's ViewController to initiate a downloaded on viewDidAppear. Problem: viewDidAppear never seems to get called (because I am using addSubView?).
I've seen other apps that do this kind of loading but need some guidance on the typical set-up. Ebay's app is a great example. All items have a default image until the item comes into view, then an activityindicator runs and the items unique image is downloaded.
Thanks for assistance.
Without actually trying it out, here's my idea:
You can use the UIScrollViewDelegate method scrollViewDidScroll: to find out when your scroll view finished scrolling and then use [UIScrollView contentOffset] to determine which part of the scroll view is visible and (CGRect)convertRect:(CGRect)rect fromView:(UIView *)view to determine the button's position within the visible part of the scroll view. Have a method that checks if the button has had its image loaded yet and if not, load it and refresh the view if necessary.
Most such apps are using a UITableView, not a plain scroll view. Joe Hewitt's Three20 framework has a TTImageView class that can do lazy image loading and is pretty well suited to this kind of use.