I'm building an iPhone application and like most I am trying to implement a UIScrollView with a UIPageControl, however I am coming across a very quirky behavior, which I assume may be a bug. Hopefully one of you has seen this before because it is driving me nuts.
Basically, the page control works fine, everything is hooked up and works normally on all accounts EXCEPT, with certain placements of the UIPageControl within the UIView, the UIPageControl will cease to render.
I'll just take screenshots of the XIB window to help illustrate... here's a placement that works perfectly fine:
http://www.jasconi.us/prob1.png
The UIPageControl is placed physically above the UIScrollView. Works great, everything is visible and working.
The next two DO NOT work:
http://www.jasconi.us/prob2.png
http://www.jasconi.us/prob3.png
The first one is simply placed below the scroll view. Doesn't render at all.
The second one is placed above the scroll view without technically being inside of it. Also doesn't render.
What the hell is up with this? I've tried using
[[self view] bringSubviewToFront:pageControl];
...to no avail.
Any ideas?
OK I found the answer to this, it's a little six degrees of Kevin Bacon.
This isn't actually a software bug, but a XIB quirk, for some reason the lower placement of the page control in combination with the default settings for autosize and anchor seem to jettison the control into outer space.
If you turn off all auto-scaling and auto-sizing and auto-anchoring and all that other crap, the controls appear exactly as you expected. The fact that it appears reliably when placed above the ScrollView is an oddity.
shrug.
Hope this helps future iPhone initiates.
Did you check to make sure that numberOfPages is not 0?
If you set a breakpoint can you see that pageControl is not nil?
I was still encountering this exact same problem, even after trying everyone's posted answers. My issue ended up being a little more "DOH":
I was using UIPageControl at the bottom of a modal FormSheet, however, I forgot to set the size of the view as Form Sheet in the xib. This caused my page control to be off the screen and never visible.
Moral: set view size (Full, Form, Page, etc) in your xib on the base view.
This will sound like a real no brainer, but I got caught out by it.
By default, UIPageControl expects to be on a dark background. IE: The dots are light gray, and white for the current page.
I used UIPageControl on it's own with no scrollview to change the time range of a graph I was rendering with drawRect:
Long story short, the graph background was white, so the page controller worked, I just couldn't see it. The solution was putting the graph itself in a subview, and making the parent that contained the page control have a dark background.
Related
EDIT**: Although someone has decided they would like to down vote without a reason I'm going to leave this up. I noticed that in viewDidLoad of my view controller container, the content view I setup was the same size as in IB. When I later tried to load other views with my view container controller, the content view had changed it's bounds. Hope this helps anyone else that has a similar issue. The excepted answer worked. Since this is a build for iOS 6 a simple check of OS version made this an easy fix.
I have a strange issue that seems to be iOS7 related. This is an iOS6 targeted app. I have followed apples own docs about creating custom container views here. The problem I'm seeing in iOS7 is the first view I load is within the proper bounds of the content view i have defined, the other two are filling the bounds of the entire screen so it hides under the navigation bar with my segmented control. I defined the view I'm loading in a separate view controller in storyboards. Is there some sort of constraint that is working against me?
I should add that I have noticed the content view I defined in my container controller is actually changing it's size after the initial view is loaded. I'm at a loss of how to stop iOS7 from changing that UIViews frame size when it really shouldn't be changing.
Here are some screenshots. Code is pretty much the same as in the apple docs, have tried a few other ideas, defining bounds etc. but I think it has something to do with IB since the content view is changing its bounds. It appears to only be doing so in iOS7.
There is actually a proper way to fix this,
Set edgesForExtendedLayout to UIRectEdgeNone for the view under the tab bar.
Of course, I might've just looked at the pictures and assumed this was your problem...sorry if its completely unrelated..
That's a known 'issue' in iOS 7. Since you can now have a blurred look through the UINavigationBars, UITabBars, ... This also causes issues in native apps (e.g. the Photos App) or APIs.
I'm developing an Enterprise app for tracking mileage and maintenance for company vehicles. I've added graphic buttons to snazz it up a bit. The buttons look the way they're supposed to look on the XIB in IB, and on the iPhone all other UIViews look correct, but on one particular UIView the graphic images are stretched way out of proportion vertically.
The first image below shows how it's supposed to look, with the three graphics buttons at the bottom. The second image shows how it's showing on the phone. The Help button on this screen cap shows normally, but it can't be counted on to stay that way.
It also is not consistent. Calling this view at any time may show the image stretched or it may not show an image at all. It rarely shows the image normally, like the Help button looks below.
The development phone is a 4S running 6.1.3. The views are set for the Retina 3.5 screen. XCode is the latest (whatever it is).
Again, it's only on this one view that the problem shows up. There is another UIView on the same view controller that is hidden when this UIView is shown. The button graphics on the other view look fine. All of the other views and view controllers use the same graphics on the UIButton, without any problem.
In Interface Builder (Xcode) you created the view using a 4.5-inch screen height.
But the device where you are seeing the problem is a 5-inch screen. So the view is resized to fit.
And when it does that, the autolayout constraints that Interface Builder put on those subviews take over to determine what they do. Those constraints are causing the heights to change.
No need to turn Autolayout off. Autolayout can be very useful, but it seems to enjoy randomly assigning the constraint "Align Baseline to:" to UIButtons after repositioning them.
Just select the UIButton/UIImageView in question inside Storyboard, locate the constraint "Align Baseline to:", tap the gear icon and select "Promote to User Constraint", and tap once more and select "Delete". This should solve your issue.
In response to the comments here, I will answer my own question: I turned Autolayout off for this view controller, and that fixed everything. This is the first app I have written since XCode has begun development for the iPhone 5, so I wasn't aware of the Autolayout feature. I'll need to understand how it works and why it did what it did.
Thanks for all your help!
I'm using a UIScrollView to display a custom UIView. When the user drags a finger across the UIScrollView, there is a noticeable delay before the display begins updating. If the user keeps touching the screen, the UIScrollView becomes very responsive after a short time. Subsequent attempts to scroll result in the same initial delay, followed by high responsiveness. This delay seriously affects the usability of the view and I would like to get rid of it.
In a test project I have written to try to get to the bottom of this issue, I have only been able to partially replicate the behaviour. The first time that the user scrolls is exactly the same - however any subsequent attempts to scroll are responsive straight away.
I have tried both setting delaysContentTouches = NO and subclassing UIScrollView so that touchesShouldBegin returns NO as suggested in multiple places online, but neither has worked.
I'm using MonoTouch on iOS 4.3, but Objective-C answers are fine. I would post code to help illustrate the issue, but since I have been unable to narrow down the problem this would be well over 1000 lines. Hopefully this is enough info to get a solution.
Does anyone know what might be causing this delay, and how I can get rid of it?
Some general suggestions for improving scrolling performance.
Have your scrolling views rasterize offscreen:
myView.layer.shouldRasterize = YES;
Set that property for each sub-view on the scrollview - do not set it for the children of those sub-views or you just eat up memory that way.
If your scrolling views do not need compositing, make sure you turn that blending off:
myView.opaque = YES;
Test using the simulator by leveraging these two features that appear on the Debug menu of the iOS Simulator:
Color Off-screen Rendered
Color Blended Layers
If that doesn't address your problem, and you have implemented UIScrollViewDelegate, double-check to make sure you are not doing anything time consuming in those methods - for example, based on your description, you might be doing something in scrollViewDidScroll, scrollViewWillBeginDragging, or scrollViewWillBeginZooming and if you are, optimize that so it happens before scrolling even begins. Also, make sure you're not doing anything in touchesBegan.
I suspect what is happening is there is some kind of interaction enabled in the content of your scroll view.
The system does not know if the initial touch down is going to be a tap on one of the subviews or a drag on the scroll view, therefore is causing a delay while it waits to see if you are going to lift your finger.
What are the subviews of the UIScroll view?
As an experiment set all the subviews of the UIScrollView to have userInteractionEnabled = NO, this will not be what you want, but its just a test. Is should scroll fine after this, otherwise I am wrong.
I'm trying to pop up a UIWebView on iPad with a web site that is specifically sized for the iPhone (320x480). I want the web view to be centered, and transition in using a zooming animation. Other apps have this functionality, but I can't seem to find out how to do it. I've tried various combinations of presentation & transition style, but no matter what I do, the web view takes up the entire screen and slides vertically to cover the screen. I've made the web view 320x480 in IB, and am using UIModalPresentationStyleFormSheet, which should make it at least slide up into the center of the screen using a small window, but that is not occurring.
anyone know what's wrong?
Are you setting the property of the parent UIViewController or the modal UIViewController? Because you should be setting the properties of the modal UIViewController before presenting the controller instead of the parent.
This might be no help at all because you're doing the right thing, but it was the first error I made when starting to use MVCs.
maybe any of the autosize property is set. just do one thing bind your webview with the code and through code try to set the frame. Hope it will work as it worked many times to me when i faced similar types of problem.
hAPPY cODING...
I'm having a fundamental problem with getting scrolling to work normally on my iPhone app. I have two views, each created in IB (although I've tried this programmatically and it makes no difference) which scroll very sloppily. Instead of the scrolling that we're used to (which is smooth and continues to scroll and eventually dampen and rubber band at the top/bottom), my scrolling only scrolls as long as my finger is in contact with the view. Swiping down quickly on a view has no more effect than swiping slowly. And when you scroll beyond the top or bottom, the view just stays there scrolled with empty area above/below.
One of my views is a UITableView and the other is a UIScrollView. Both have exactly the same problem and are in different XIBs, coupled to different classes, so this is why I think I'm missing a key concept in general.
My UITableView is a child to a UIView (since there is also a nav bar at the top) with my UIViewController's view connected to the UIView. The referencing outlets datasource and delegate are both hooked to the UITableView. Nothing is subclassed here aside from the ViewController of course which has overrides to populate the table.
In the second instance, I again have a non-subclassed UIView which my UIViewController's view is connected to. I have a subclassed UIScrollView as a child to the UIView and then a have a subclassed UIView (with larger size than the scroll view) as a child to the subclassed UIScrollView. This in itself seems ridiculously complicated to me, but I was not able to get scrolling working at all with fewer than 3 views (again there is a nav bar at the top of the non-subclassed UI-View). I am overriding drawRect: in my UIScrollView, which is putting the content up fine except for this scrolling issue.
Is there something I'm doing wrong organizationally? I've come across many suggestions on stackoverflow and other sites for UIScrollView and none make a difference. And I don't see anyone having scrolling issues with UITableView. I'm not pasting in any code because I would have to post full classes at this point (making the post ridiculously long) and I believe the problems to really lie with the way I'm using IB.
Thanks!!
OK, it turns out that this has nothing to do with UIKit. This code is part of a game I'm developing using cocos2d and that framework is what is causing the problem. For those who are developing on cocos2d, you cannot use FastDirector and expect scrolling to work in UIViews. Just remove any code like [[Director sharedDirector] useFastDirector] and everything will be fine.
Some code might help narrow down your problem.
In the mean time, try creating a new project in Xcode using the 'Navigation-based Application' template and take a look at how the navigation controller is being created in MainWindow.xib. Take a look at how the UITableViewController subclass called 'RootViewController' is defined and how the corresponding xib is setup too. You'll notice there is no UIScrollView explicitly defined anywhere but you get scrolling functionality from the tableview controller 'for free'.
This should give you a pretty good starting point down the right path. I question the need for overriding drawRect: without seeing some code or fully understanding your goal.
Take a look at:
http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UIScrollView_Class/Reference/UIScrollView.html
http://developer.apple.com/iPhone/library/featuredarticles/ViewControllerPGforiPhoneOS/UsingNavigationControllers/UsingNavigationControllers.html