I have built an app using the IOS 9 SDK.
I am printing using the UIPrintInteractionController and a subclass of UIPrintPageRenderer.
When the print dialog is displayed on the iPad or iPhone, UIPrintPageRenderer's drawPageAtIndex:inRect method is not called and the preview area on the dialog is just a gray box with a button that says Page 1.
This is an app that was originally written in the IOS 6 era and I am trying to update it for IOS 9, so perhaps I need to improve something.
Does anyone know what is happening here?
Thanks!
I don't understand what's happening exactly, but I had the same problem and fixed it by
1) ensuring that logic in my overrides is being executed on the UI thread
2) moving my AddPrintFormatter call to the constructor method instead of calling from a NumberOfPages override (which allowed me to delete this override property).
There seems to be some weird threading behavior now when overriding UIPrintPageRenderer (at least in Xamarin's implementation).
For example, adding this simple override causes a UIKit Consistency error for me:
public override nint NumberOfPages
{
get
{
return base.NumberOfPages;
}
}
So it seems the base method begins execution on the UI thread when there isn't an override, but the subclass's override begins execution on a worker thread.
The iOS9 SDK Release Notes document says:
"Apps that subclass UIPrintPageRenderer or UIPrintFormatter to draw content for printing must be built with the iOS 9 SDK for the preview to display. The behavior of UIPrintPageRenderer has been updated to call drawPageAtIndex:inRect: multiple times with potentially different page sizes and margins. Various methods on UIPrintPageRenderer may be called from a non-main thread, but never from multiple threads concurrently."
Turns out I was missing the numberOfPages override in the UIPrintPageRenderer derived class. The preview works after adding this override.
I'm giving carchase an upvote since the post tangentially mentioned the numberOfPages method, but my actual problem was not as subtle as suggested by carchase's post ;-).
It sounds like you need to add the print formatter.
[myRenderer addPrintFormatter:viewFormatter startingAtPageAtIndex:0];
Related
I have recently started to learn iOS with obj-c from "iOS Programming The Big Nerd Ranch Guide 4th Edition". This edition was released in 2014 and is written with Xcode 5.
I am trying to make a simple app with two buttons and two labels. The labels are connected to two arrays and when a button is pressed an object from the corresponding array is shown in the corresponding text label (it's the Quiz app in chapter 1).
I created the project as a Single View app in Xcode 6, and put all my objects in the view controller class. I have two labels two buttons two arrays and an int to keep track of the object that has to be displayed from the array.
In the book it says that I should initialize the arrays in the initWithNibName method. I tried that but for some reason it never gets called. So I changed the initialization of the arrays to the init method. They initialize fine but when they are called from another method they are nil. Do you have any idea why this is happening?
The second issue I'm having is that I can't manage to get the contents of the storyboard on screen. It says that I'm supposed to make an instance of the ViewController inside the AppDelegate and make it the root window controller but all I get is a white window (or black in case I don't set the color).
UPDATE: I changed the intialization of the arrays from the init method to the viewDidLoad method and now they seem to be working fine. Nothing on the screen though.
It sounds like you're initializing your UIViewController from the app delegate AND a storyboard. If you create a new project in XCode, a "Single view application", you won't have to touch the app delegate at all in order to get something on the screen.
I believe both your problems are related to this, since it sounds like you're seeing an empty UIViewController on the screen (the one you create in the app delegate)
As for the initialization of your array, viewDidLoad is a popular place to do this.
If you are using storyboards, the method initWithNibNameOrNil will not be called. In the BNR book, it teaches you to use XIB files, which do use this method. If you are trying to follow the tutorials, I would suggest using XIB files.
For use of a book, I would suggest downloading whatever version of Xcode is being used for that book -- otherwise you will be running into a lot of confusing problems while learning.
If you would like to download previous version of Xcode, refer to this post:
How to download Xcode DMG or XIP file?
I have a graph built in Paintcode that I am showing in a UIView. It works fine in the App but will not render in storyboard. I have read a host of different posts about overriding init frame, and init coder. However, I can't find a specific example that helps me with my problem, by showing the practical use of these overrides.
The graph takes 14 variables to produce a bar chart. Here is the class code
import UIKit
#IBDesignable
class graphRisk: UIView {
override func drawRect(rect: CGRect) {
StyleKitGraph.drawRiskGraph(ehsScale: ehsScale, ciScale: ciScale, stratScale: stratScale, qaScale: qaScale, delScale: delScale, leadScale: leadScale, peopScale: peopScale, hrmScale: hrmScale, pmScale: pmScale, costScale: costScale, finScale: finScale, assScale: assScale, itsScale: itsScale, engScale: engScale)
}
}
It looks good in the App, and it is no big deal if it doesn't render as the variables are coded, and the design is fine, however, I removed the #IBDesignable tag and it still errors the same.
Finally, how do I get the UIView to update when I enter the view controller it resided in?
So the questions are;
1 How do I get render to work for this code example?
2 Is there a way to not render the view, and stop the error that way?
3 Do I need to worry about the error as the App runs fine?
4 How do I get the UIView to refresh. What is the syntax for .setNeedsDisplay() etc? I tried lots of things and none updated or reloaded or refreshed.
As always I truly welcome all help, and thank you.
Not sure what version of Xcode you are using. I am using Xcode 6.4.
I, like you, have researched for days on many websites and tried many solutions. None of them worked. At last, I removed the #IBDesignable to my custom UI class. Not only did the error went away, the instance of the custom UI class previewed fine in Main.storyboard.
Perhaps, in the new development of Xcode, #IBDesignable is no longer necessary.
I was wondering whether it is possible / how it is possible to code a class so it can be run on different iOS versions in Objective-C. For example the VisualEffectView is only available in iOS8 and after. Is it possible to declare a VisualEffectView if iOS >= 8 and UIView if not? If so can this be done within a header file?
I want to create an alert box to appear on top of a view controller when a save completes or error occurs. Depending on the iOS version it would be nice if a fancy blurry view is used or just a flat UIView.
In an if statement, use NSClassFromString. You'll discover immediately that UIVisualEffectView doesn't exist when it returns nil, and thus you can take one branch if it exists and another if it doesn't:
if (!NSClassFromString(#"UIVisualEffectView")) {
// ... use UIView ...
} else {
// ... use UIViewVisualEffectView ... {
}
As of iOS 5 you can the following syntax.
if ([UIVisualEffectView class]) {
// Create and use a UIVisualEffectView
}
This will occasionally bite you, NSMapTable is available in iOS versions prior to iOS 6, but was only "officially" available in iOS 6. When attempting to use it in iOS 5 there was some sporadic undocumented behavior.
As many have suggested, you can use the NSClassFromString function to find out at run time if the OS version has the class. If it doesn't (that is iOS 7 devices) and you still want live blurring, I'd recommend LiveFrost.
I'm using the VFR PDF viewer library in my app, where I present it thus:
ReaderDocument *document = [ReaderDocument withDocumentFilePath:pdfFile password:nil];
ReaderViewController *vc = [[ReaderViewController alloc] initWithReaderDocument:document];
[self.navigationController pushViewController:vc animated:YES];
If I run on iOS7, everything works fine.
If I run my app on iOS8, the willRotateToInterfaceOrientation method in ReaderViewController never gets called, so when the device is rotated the document doesn't get reformatted correctly.
However, if I run the demo app that comes with the library on iOS8, the willRotateToInterfaceOrientation in ReaderViewController does get called, which leads me to believe the library is ok, and I'm doing something wrong (or neglecting to do something) in my app.
I'm rather puzzled at this behaviour. Why doesn't willRotateToInterfaceOrientation get called in my app on iOS8, but it does under the other variations? How can I try to track this down?
I finally managed to resolve my problem; here is what the issue was in case anyone else has the same problem.
My ReaderViewController was being presented from a class that had implemented viewWillTransitionToSize:withTransitionCoordinator:, so the deprecated methods on child view controllers weren't being called.
Also in that implementation it wasn't calling
[super viewWillTransitionToSize:size withTransitionCoordinator:coordinator]
and so the viewWillTransitionToSize:withTransitionCoordinator: method of all child view controllers wasn't being called either.
The fix was to add a call to
[super viewWillTransitionToSize:size withTransitionCoordinator:coordinator]
into the parent VC's viewWillTransitionToSize:withTransitionCoordinator: method, subclass ReaderViewController, then add a viewWillTransitionToSize:withTransitionCoordinator: to my subclass to call the appropriate methods in ReaderViewController.
Simply because willRotateToInterfaceOrientation is no more called in iOS8, it is deprecated.
If the new rotation methods are not implemented, and a project is
compiled with the iOS 8 SDK, the view controllers -will not receive
calls- to the deprecated rotation methods.
A similar question to yours can be found here
Citation of #mluisbrown :
The rotation methods are deprecated in the iOS 8 SDK. This will have
no effect at all on apps built with the iOS 7 SDK, even running in iOS
8 and probably several future versions of iOS.
I struggled a bit with some kind of a similar problem to yours. I tried following Apple recommendation to use viewWillTransitionToSize, which in my case did not solve my problem because this only gets triggered on changes from regular to compact for example an not on rotation.
viewWillTransitionToSize:withTransitionCoordinator: to make
interface-based adjustments.
Which is detailed in apple documentation
Also a video of WWDC 2014 explains this but I can't remember which video it was. Perhaps the one on What's new in Cocoa touch or the one on View Controller Advancements in iOS 8.
EDIT
Note that in my case viewWillTransitionToSize, as explained, was not called because I wasn't changing from regular to compact so there was no size transition, strictly speaking for Apple.
The only solution I fount was to handle this manually in the viewDidLayoutSubviews of the corresponding view controller.
In my case I wanted to keep track of the top cell displayed in a tableview with autolayout. As it wasn't tracked automatically by the system, I had to check that manually and scroll manually to the adequate cell on rotation. That's why I did it that way. It's quite "heavy" but works in my case.
I would also be interested if anyone has an easier solution.
I have an app with a custom text editor that implements the UITextInput protocol. In iOS 6, Apple added one new required method to the protocol:
- (NSArray *)selectionRectsForRange:(UITextRange *)range
I've implemented this, but I can't seem to find a way to trigger it. At least in the way my app works, it seems to never get called by the text system. Does anyone know what it's used for?
This method is only used by subclasses of UITextView. This is the only method that would give you the system selection and loupe. This is what I was told at WWDC.
I am working on my own DTRichTextEditor as well and I implemented it nevertheless, maybe one day we get the selection/loupes also for our own UIViews that are not derived from UITextView.