I am developing an app using SDK 8.1, Apple LLVM 6.0 and Xcode 6.1.1. The deployment target is 6.0. I'm using NSOperationQueue and I want to use QoS whenever it's available.
The code I'm using is:
if ([self.operationQueue respondsToSelector:#selector(setQualityOfService:)]
&& (&NSOperationQualityOfServiceUserInitiated)) {
[self.operationQueue performSelector:#selector(setQualityOfService:) withObject: NSOperationQualityOfServiceUserInitiated];
} else {
//Other stuff not related to the scope of this question
}
The error I get is:
Use of undeclared identifier 'NSOperationQualityOfServiceUserInitiated'
I added the if (&NSOperationQualityOfServiceUserInitiated) part to check if this constant exists. This code worked with older versions of Xcode/Obj-C Compiler.
I am able to use selectors with performSelectorWithIdentifier but what about constants that do not have a defined value in the docs? The value of this constant is set by NSQualityOfServiceUserInitiated but there is no definition for this value that can be hardcoded.
How do I fix that?
There are several things wrong with the code.
NSOperationQualityOfServiceUserInitiated is a native type (NSInteger) so you can't use it the way that you are in either line.
The qualityOfService is a property of type NSQualityOfService. Your attempt to pass an argument to the qualityOfService method (getter method) makes no sense. If you are trying to set the quality of service, you need to call the setter but you can't use performSelector.
You want:
if ([self.operationQueue respondsToSelector:#selector(qualityOfService)]) {
self.operationQueue.qualityOfService = NSOperationQualityOfServiceUserInitiated;
} else {
//Other stuff not related to the scope of this question
}
This code will compile fine as long as your Base SDK is iOS 8.0 or later. The Deployment Target doesn't matter.
If you also want to build this code with Xcode 5 or earlier (a Base SDK of iOS 7 or earlier) then you need to wrap the code with the proper compiler directives to check for the Base SDK.
Related
After upgrading from XCode 10.0 to 11
I am getting the error 'name' is unavailable: not available on iOS
This is during Build for Swift 4.2 on XCode 11.0 and 11.1 , I can still build using XCode 10
This is happening in the code of one of the Objective C external libraries we have been using through Cocopods.
return [(NSNumber *)[table[state] objectForKey:[rule name]] unsignedIntegerValue];
I can work around the issue by renaming the variable name to ruleName , but I would rather not do this.
Why is Xcode objecting to a variable name of name? Is this an Xcode but or is it something I can fix in the build settings
Edit
The specific pod is NUI 0.5.5
In module NUIPShiftReduceGotoTable.m
- (NSUInteger)gotoForState:(NSUInteger)state rule:(NUIPRule *)rule
{
return [(NSNumber *)[table[state] objectForKey:[rule name]] unsignedIntegerValue];
}
Apple made a change that can break previously compiling code in Xcode 11.0/11.1. Previously the compiler would be fine with passing the 'name' message to an object that it didn't know the type of. This can happen for many reasons in the weakly typed Objective-C world.
Currently in Xcode 11.1 you can do.
id x = nil;
[x name];
And this will compile, no problem. But:
NSObject *x = nil
[x name];
won't compile due to the compiler identifying the most likely selector being the API_UNAVAILABLE one in NSLayoutAnchor.h (maybe).
If the compiler had more information it can map the correct selector. This might be as simple as including the header for whatever has name property in the .m file that is failing.
My guess is something like in NUIPShiftReduceGotoTable.m you add a line
#import"NUIPRule.h"
I have this code from a library I am using.
#ifdef __IPHONE_8_0
if (&SKStoreProductParameterAffiliateToken) {
if (self.affiliateToken) {
[appParameters setObject:self.affiliateToken forKey:SKStoreProductParameterAffiliateToken];
if (self.campaignToken) {
[appParameters setObject:self.campaignToken forKey:SKStoreProductParameterCampaignToken];
}
}
}
#endif
Xcode is saying that the first line will always evaluate to be true but what is this line doing exactly? I never saw a if with & and a constant in that way.
SKStoreProductParameterAffiliateToken is defined as
SK_EXTERN NSString * const SKStoreProductParameterAffiliateToken NS_AVAILABLE_IOS(8_0);
What is the developer trying to check, the address of a constant? Is he trying to check if the version of iOS has this constant defined and by doing that, he is trying to check the instruction inside the if should run? But he already has ifdef __IPHONE_8_0... (??!!)
I don't get it.
Anyway I am compiling for iOS 9.3, so I can delete the if and the ifdef, right?
It is a check to see if a weak-linked symbol is available. If the library/framework containing the symbol has been weakly linked and is not available its address will evaluate to NULL and the if condition will be false.
See Using Weakly Linked Methods, Functions, and Symbols in Apple's Using SDK-Based Development for full details.
#ifdef __IPHONE_8_0 checks if Xcode should compile code inside. Ohterwise older version of Xcode will show an error about unknown variable SKStoreProductParameterAffiliateToken.
But when using newer Xcode version (with iOS SDK 8+), we may still can set a lower minimum target for our project. In this case to avoid crash on devices with lower than iOS 8 version we should check first if variable, class, method or function exists.
In your case, we are checking if pointer to SKStoreProductParameterAffiliateToken is not NULL, which means app is currently running at least on iOS 8.
I'm creating an app that works with CloudKit framework (iOS 8-only) but still want to keep compatibility with iOS 7.1, with no CloudKit functionality, of course. Apple documentation recommends checking for optional classes like this:
if ([CKRecordID class]) {
// iOS 8 code
} else {
// iOS 7 code
}
This works. On the other hand, if I write
#interface Foo : NSObject
#property (nonatomic) CKRecordID *recordID;
#end
anywhere in the code, the app will crash on iOS 7 when loading the Foo class. How can I define properties with those optional classes?
You could use the forward declaration
#class CKRecordID;
but you will need runtime checks for the iOS version, such as
[[NSProcessInfo processInfo] operatingSystemVersion]
Other solutions for detecting the iOS version are shown here or here.
But how about two different builds for different iOS versions?
You can make your property recordId of type id or NSObject.
And when you need to access this property (after checking that your runtime is iOS8+), you cast it to CKRecordID class.
I subclass PFObject exactly as described here.
Then I create a new instance of the subclassed object without data, but since Swift 1.2 I get an error (It did work perfectly before):
var test = Armor(withoutDataWithObjectId: "1234567890")
-> Xcode complains:
"Incorrect argument label in call (have 'withoutDataWithObjectId:',
expected: 'className:')"
Why className? It should get the class name from the class function parseClassName
And I can under no circumstances create a new object with objectId but no data (which I MUST have to fetch it from the local datastore)
This is super annoying as my app doesn't compile any longer.
Update to the newest Parse SDK, available here.
The issue is caused due to necessary adaptions in the Parse SDK after the Swift language update. This issue also occurs with the most recent update to Swift 2.2. The newest (as of today) Parse SDK release 1.13.0 already fixes this.
UPDATE
Parse iOS SDK 1.13.0 has a typo and the function PFUser(withoutDataWithObjectId:) is called PFUser(outDataWithObjectId:). So upgrading the Parse SDK alone does solve this. Until this is fixed a temporary workaround would be to extend PFObject with a convenience initializer. To do this add a new Swift file to your project and insert this:
import Parse
extension PFObject {
convenience init(withoutDataWithObjectId objectId: String?) {
self.init(outDataWithObjectId: objectId)
}
}
It may be a little late to answer this question.
I use swift 1.2, and v 1.7.5 Parse SDK, and it works totally fine.
however, make sure you have define objective-c bridging header in "build setting".
and try to run it, even though there may reports some error
I am using ECSlidingViewController for "hamburger" menu. I am using SDK 7.0 but I changed deployment target to iOS 6.1 and now I am trying my app with older iOS then 7. The problem is with setEdgesForExtendedLayout. There is older ECSlidingViewController for older system versions. So my question is how can I change to use old version for iOS 6.1 and older and newer version for iOS 7.0 and newer. I include files from both ECSlidingViewController projects (not by cocoapods but if it is need then it's not problem to change it). I guess I need check for OS version and then change imports but I am not sure if it is enough and what's best name convention for both project. I guess they should be in different folders (like ECSlidingViewController and ECSlidingViewControllerOld) but class should be same name, is it right?
Edit: Example of code with edgesForExtendedLayout:
- (CGRect)underLeftViewCalculatedFrameForTopViewPosition:(ECSlidingViewControllerTopViewPosition)position {
CGRect frameFromDelegate = [self frameFromDelegateForViewController:self.underLeftViewController
topViewPosition:position];
if (!CGRectIsInfinite(frameFromDelegate)) return frameFromDelegate;
CGRect containerViewFrame = self.view.bounds;
if (!(self.underLeftViewController.edgesForExtendedLayout & UIRectEdgeTop)) {
CGFloat topLayoutGuideLength = [self.topLayoutGuide length];
containerViewFrame.origin.y = topLayoutGuideLength;
containerViewFrame.size.height -= topLayoutGuideLength;
}
if (!(self.underLeftViewController.edgesForExtendedLayout & UIRectEdgeBottom)) {
CGFloat bottomLayoutGuideLength = [self.bottomLayoutGuide length];
containerViewFrame.size.height -= bottomLayoutGuideLength;
}
if (!(self.underLeftViewController.edgesForExtendedLayout & UIRectEdgeRight)) {
containerViewFrame.size.width = self.anchorRightRevealAmount;
}
return containerViewFrame;
}
I am not a fan of including duplicate versions of libraries, as this creates a big problem with naming, and a lot of work to refactor all old classes to have some *-OLD suffix. Since you have access to the source, you can modify the newer version like so:
if(NSFoundationVersionNumber > NSFoundationVersionNumber_iOS_6_1)
{
[vc setEdgesForExtendedLayout:UIRectEdgeNone];
//Any other iOS7-specific code.
}
First, the easiest way to do it will be have the most recent version of component that support the lowest deployment target.
But if you really want to have different version for each iOS, I don't know better solution, than just rename all classes from, for example, older version (because there was only two classes) and manage creation of this controller programmatically, because there's no way to set different class for different iOS version in xib's or storyboard's. You need to wrap each and every call of this component with iOS version check ( How to check iOS version? ).
Imports and variables you can leave for each version of component without check.
The trick you mentioned failed in this case, because it works good for different architecture, because binaries for different architectures will be included in final app and that's named fat binary, but there's the same architecture for iOS6 and iOS7 ( only one new in iOS7 - arm64). So you can't wrap only includes with preprocessor macros and get fat binary with different code for each iOS version.
I hope you've understood something from my explanation.
It seems that the only thing preventing you from using the new version with iOS 6 is the lack of topLayoutGuide and bottomLayoutGuide, which if available would just return lengths of zero anyway.
Why not "backport" those methods in your controller?
- (id<UILayoutSupport>)topLayoutGuide
{
CustomLayoutGuide * guide = [CustomLayoutGuide new];
guide.length = SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(#"7.0") ? super.topLayoutGuide.length : 0.0;
return guide;
}
And the helper class
#interface CustomLayoutGuide : NSObject <UILayoutSupport>
#property(nonatomic) CGFloat length;
#end
#implementation CustomLayoutGuide
#end
IMHO the easiest thing to do (and probably the best though) is to take the current ECSlidingViewController and integrate part of the old when edgesForExtendedLayout is not available (e.g. if ([self respondsToSelector:#selector(edgesForExtendedLayout)]) { /*...*/} ). This should be pretty easy and fast to do since the old ECSlidingViewController just consists of two files and these files are also present in the new ECSlidingViewController.
You could make your life even easier when doing this by using a diff tool to be sure of what you should add.