The last 2 days i brooded over a strange behavior i found in my iOS app. It was one of these moments when you start to have doubts about everything. I found the problem and fixed it. But i want to write this here to search for answers and gain knowledge about the system behind.
I am the developer of "Controller for HomeKit", an app to control HomeKit devices. In HomeKit you have HMActionSets to execute many changes at once. E.g. Turn on all lights.
Executing HMActionSet is a basic functionality and worked always. Here with a swipe of UITableViewCell.
let performAction = UIContextualAction(style: .normal, title: AppStrings.Actions.perform, handler: { (ac: UIContextualAction, view: UIView, success: #escaping (Bool) -> Void) in
self.home?.executeActionSet(selectedActionSet, completionHandler: { (error: Error?) in
if let err = error {
UIApplication.printToConsole(text: err)
success(false)
return
}
success(true)
})
})
BUT suddenly it stopped working flawlessly with a new development version. It took me a while to reproduce the situation, when it wasn't executing the action set.
Every time i start the app from scratch, everything works.
If i execute the HMActionSet right after navigating from the previous UIViewController, everything works. (Most common use case)
It stops working when being in the view, press the home button, reentering the app. After that all executions won't work, until going one view backwards and forward again.
Console logs this error:
Error Domain=HMErrorDomain Code=2 "Object not found." UserInfo={NSLocalizedDescription=Object not found.}
I walked backwards every commit until the problem was solved. After digging in the dark in a too big commit, i found the root cause.
But why am i not getting compile errors? Why does going to the home screen breaks it?
For a new feature i needed a new way to identify a HomeKit object on multiple devices, because the .uniqueIdentifier parameter is salted on every device.
import Foundation
import HomeKit
protocol Identifyable {
func getUniqueIdentifier() -> String?
}
extension HMActionSet: Identifyable {
func getUniqueIdentifier() -> String? {
return self.name.toBase64()
}
}
I created a swift protocol and made an extension to HMActionSet. Of course now that i found the error it looks stupid, to name the method like a getter. But this should not be the discussion now. It seems like this methods overrides the attribute of HMActionSet. When executing the actionSet internal functions accidentally use the wrong uniqueIdentifier, therefore the error is correct. (No object found).
/*!
* #brief A unique identifier for the action set.
*/
#available(iOS 9.0, *)
open var uniqueIdentifier: UUID { get }
If i name the method func uniqueIdentifier() -> String? Xcode immediately shows me a warning.
Method 'uniqueIdentifier()' with Objective-C selector 'uniqueIdentifier' conflicts with getter for 'uniqueIdentifier' with the same Objective-C selector
As i know HomeKit is written in Objective-C. I am using swift 4.
My questions to you:
Why are there no compiler errors (getUniqueIdentifier())?
If its a runtime problem mixing a swift extension into a objective-c framework, why does it only occur when reentering the app and not at the first start or later?
Looking forward to read your explanations about the problem that stole my sleep. :)
so i have this weird problem that's been bugging me for the last few hours.
I have a framework in which I created a protocol named ChatDelegate (code bellow)
public protocol ChatDelegate: class {
func chat(_ chatCollectionView: UICollectionView, didSelect message: Message)
}
and a ViewController (not in the framework), which conforms to the ChatDelegate, like so
extension ChatContainerViewController: ChatDelegate {
func chat(_ chatCollectionView: UICollectionView, didSelect message: Message) {
print("did select")
}
}
but the compiler still complains that the ChatContainerViewController does not conform to the protocol and I don't understand why?? The function has the exact same header (I also tried putting public in front ...didn't help).
Any help would be much appreciated.
UPDATE
I figured it out. The problem was that I had Message class in my project and in the framework and the compiler didn't know which one to choose. Adding ModuleName in front (ModuleName.Message) fixed it. :D
I had the same issue. The file that defined the protocol had a target membership in both the framework and the application targets. I solved the issue by making the file that defined the protocol only have a target membership in the framework and then adding an import <FrameworkName> to the code in the application target that needed to use the protocol.
I am starting to learn Swift, and have been following the very good Stanford University video lectures on YouTube. Here is a link if you are interested or it helps (although it isn't required to understand my problem):
Developing iOS 8 Apps with Swift - 2. More Xcode and Swift, MVC
While following the lectures I got to a point where (as far as I could tell) my code was identical to the code in the video but on my system I got a compiler error. After a lot of trial and error I have managed to reduce my code to two examples, one of which generates an error, the other or which doesn't, but I have no idea what is actually causing the error or how to resolve it.
The code which creates the error is:
import UIKit
class BugViewController: UIViewController
{
func perform(operation: (Double) -> Double) {
}
func perform(operation: (Double, Double) -> Double) {
}
}
This creates the following compiler error:
Method 'perform' with Objective-C selector 'perform: ' conflicts with previous declaration with the same Objective-C selector
By simply removing the sub-classing of UIViewController the code compiles:
import UIKit
class BugViewController
{
func perform(operation: (Double) -> Double) {
}
func perform(operation: (Double, Double) -> Double) {
}
}
Some other information which may or may not be relevant:
I have recently upgraded to Yosemite.
When I installed Xcode, I ended up with a Beta version (Version 6.3 (6D543q)) because (if I remember correctly) this was the version I needed to run on my version of OS X.
I am half hoping this is a bug in the compiler because otherwise this doesn't make any sense to me. Any help very gratefully received!
I myself am also taking the Standford course and I got stuck here for a long time too, but after some searching, I found something from here: Xcode release notes and it mentioned something below:
Swift 1.2 is strict about checking type-based overloading of #objc
methods and initializers, something not supported by Objective-C.
// Has the Objective-C selector "performOperation:".
func performOperation(op: NSOperation) { /* do something */ }
// Also has the selector "performOperation:".
func performOperation(fn: () -> Void) {
self.performOperation(NSBlockOperation(block: fn))
}
This code would work when invoked from Swift, but could easily crash
if invoked from Objective-C. To solve this problem, use a type that is
not supported by Objective-C to prevent the Swift compiler from
exposing the member to the Objective-C runtime:
If it makes sense, mark the member as private to disable inference of #objc.
Otherwise, use a dummy parameter with a default value, for
example: _ nonobjc: () = (). (19826275)
Overrides of methods exposed
to Objective-C in private subclasses are not inferred to be #objc,
causing the Swift compiler to crash. Explicitly add the #objc
attribute to any such overriding methods. (19935352)
Symbols from SDKs are not available when using Open Quickly in a
project or workspace that uses Swift. (20349540)
what i did was just adding "private" in front of the override method like this:
private func performOperation(operation: Double -> Double) {
if operandStack.count >= 1 {
displayValue = operation(operandStack.removeLast())
enter()
}
}
Objective-C does not support method overloading, you have to use a different method name. When you inherited UIViewController you inherited NSObject and made the class interopable to Obj-C. Swift on the other hand does support overloading, that's why it works when you remove the inheritance.
As it has already been answered, ObjC doesn't support method overloading (two methods with the same name) and In swift 2 under Xcode 7 there are two options to solve this kind of problems. One option is to rename the method using the attribute: #objc(newNameMethod:)
func methodOne(par1, par2) {...}
#objc(methodTwo:)
func methodOne(par1) {...}
another option to solve this problem in Xcode 7+ is by applying #nonobjc attribute to any method, subscript or initialiser
func methodOne() {...}
#nonobjc
func methodOne() {...}
The problem is UIViewController is an #objc class. When inheriting from UIViewController, BugViewController is also a #objc class.
This means it must conform to the rules of Objective-C selectors (the name of a method). The methods func perform(operation: (Double) -> Double) and func perform(operation: (Double, Double) -> Double) both have the same selector #selector(perform:). This is not allowed.
To resolve this, use different names: like func perform1(operation: (Double) -> Double) and func perform2(operation: (Double, Double) -> Double).
I think the best way to handle this is to give your perform() methods more descriptive names. What do these methods do? How do they change the state of the view controller? Look at the other UIViewController methods to get a feel for the style of method naming, or read Method Names Should Be Expressive and Unique Within a Class
From https://developer.apple.com/library/ios/releasenotes/DeveloperTools/RN-Xcode/Chapters/xc6_release_notes.html under "Xcode 6.3 Release Notes" -> "Swift Language Changes" you find
Swift now detects discrepancies between overloading and overriding in the Swift type system and the effective behavior seen via the Objective-C runtime.
I got the same error due to having having two methods with the same Obj-C signature:
static func prepareForUpSyncing(obj : NSManagedObject!) -> Bool
static func prepareForUpSyncing(objs : [NSManagedObject]!) -> Bool
I didn't want to mark one of them as #nonobjc due to possibility of unforseen consequences at runtime. (Someone can correct me if there is no possibility)
Resolved it by using Swift's external parameter name feature (I made external name same as local name) to the second method, which effectively changes the Obj-c method signature:
static func prepareForUpSyncing(objs objs : [NSManagedObject]!) -> Bool {
So I just downloaded Xcode 7 GM, and out pops this error:
fatal error: unavailable function can't be called: file /Library/Caches/com.apple.xbs/Sources/swiftlang/swiftlang-700.0.59/src/swift/stdlib/public/core/RangeReplaceableCollectionType.swift, line 329
Any ideas on how to resolve this?
Turns out, I had a protocol with the function extend as a requirement.
public protocol Appendable: Initiable, SequenceType
{
mutating func insert(_: Generator.Element)
mutating func append(_: Generator.Element)
mutating func extend<S: SequenceType where S.Generator.Element == Generator.Element>(_: S)
}
Now extend has been renamed to appendContentsOf, however Xcode stayed shush when it came to my protocol requiring it (a bug). Whenever I called extend on conformant types (in my case Array, Dictionary and Set), instead of telling me that extend had been renamed, it just resolved the issue by using a function guaranteed by Appendable, also extend. And guess who provided the implementation.
That's right.
PS: I ran the migrator before doing all of this, and it should have resolved this issue, but eh.
I have an iOS swift program that compiles and runs fine on Xcode Beta2. When I downloaded beta4, I got a few syntax errors for the new swift language which I corrected. I now get this error:
<unknown>:0: error: unable to execute command: Segmentation fault: 11
<unknown>:0: error: swift frontend command failed due to signal (use -v to see invocation)
The problem is that it does not tell me where this error is so that I can further troubleshoot it. Where can I type -v in order to "see the invocation" and troubleshoot further? Without this, there is absolute no way to figure out the problem. Thanks in advance.
Here's how I was able to find out what the problem was:
Click on the issue in the issue navigator (⌘ + 4, then click on the line with the red ! at the start)
At the bottom of the file that appears, there should be a line that says something like:
1. While emitting IR SIL function #_TToZFC4Down8Resource12getInstancesfMS0_U__FTSS6paramsGVSs10DictionarySSPSs9AnyObject__9onSuccessGSqFGSaQ__T__7onErrorGSqFT5errorCSo7NSError8responseGSqCSo17NSHTTPURLResponse__T___T_ for 'getInstances' at /path/to/file.swift:112:5
The location where your error occurred is at the end of that line. (In this case, on line 112 of file.swift in getInstances).
I was trying to add the PayPal framework to my iOS Project (Xcode 7.2 and Objective C language). When building it did not throw any error, but when I tried to archive the Project and make the IPA, I was getting that error
unable to execute command: Segmentation fault: 11
Screenshot:
After struggling for a long time, I disabled the Bitcode in Project's Target > Build Settings > Enable Bitcode. Now the project can be archived. Please check the following screenshot.
Can't really give a straight solution on this (although I'm sure it's an Apple bug), but I just came across the exact same error message and happen to solve it. Here's what I did:
In General
Comment out recently changed Swift code (check commits) until the app compiles again
Command-click each called method in the failing line and check if there could be an ambiguity
My Example
In my case (I was using the XMPPFramework written in Objective-C) the failing code looked like this:
for roomMessage: XMPPRoomMessage in self.messages {
let slices = split(roomMessage.nickname(), { $0 == "_" }, allowEmptySlices: false)
}
Once I replaced roomMessage.nickname() with "0_test" the code didn't fail any more. So I command-clicked the method nickname() (twice) and here's what I saw:
My guess was that the Swift 1.1 compiler has problems with figuring out which method to call if the exact type of an object is not clear. So I made the type of roomMessage explicit and got another error which I fixed by removing the braces behind the nickname() method call. This made my app build again. Here's the working code:
for roomMessage: XMPPRoomMessageCoreDataStorageObject in self.messages {
let slices = split(roomMessage.nickname, { $0 == "_" }, allowEmptySlices: false)
}
I hope this helps someone out there to investigate the issue more quickly than I did.
I also had the same problem,
when I cleaned the derived data
Remove all removed derived data from Trash as well.
Stop Xcode, restart it and clean build
It should be fixed now.
In my case this error because I use Class name for variable
var MYClass : MYClass {
get {
return.....
}
}
And this fixes my problem
var myClass : MYClass {
get {
return.....
}
}
My problem was that I tried to mimic static variables with the so-called module approach (the Module design pattern). So, I had something like that (just a simple static reference to an operation queue declared at the level of a swift file):
let globalQueue: NSOperationQueue = {
let queue = NSOperationQueue()
queue.suspended = false
queue.maxConcurrentOperationCount = NSOperationQueueDefaultMaxConcurrentOperationCount
return queue
}()
So, that worked fine in Xcode 6.x.x, but ceased to compile in Xcode 7beta. Just want you guys to be aware of it.
P.S. In general, I managed to find out what was wrong from the logs (see the screenshot attached). Hope this saves you some time.
I got Segmentation fault when I called a protocol function the same protocols extension.
I had a code something in the line with this:
protocol Rotatable {
func rotate() -> Self
}
extension Rotatable {
func rotate(steps: Int) {
for _ 0..<steps { self.rotate() }
}
}
When I later made an object and declared that it would follow the Rotatable protocol I got Segmentation fault 11 and the program crashed.
Ex: this would cause Segmentation fault and crash Xcode
struct SomeStruct : Rotatable {
}
If I however first implemented the function rotate() in SomeStruct and then afterwards declared that it conformed to Rotatable there where no problem.
I had a similar today and tried the steps described here including removing files I had recently modified. Nothing seemed to work. I tried something that had been suggested when SourceKit would crash in Xcode.
I when into the derived data directory and deleted everything. The location is listed under "Preferences -> Locations -> Derived Data" There is an arrow icon right next to the path which opens finder with that directory selected. Select all the directories inside and delete them. Close Xcode and Reopen it. That made the problem disappear for me.
I think that some intermediate file is getting corrupted and the compiler does not know how to handle it.
I get this error because a silly mistake!!
in a class I defined
var url: String!?
:)
So it seems that this description is a multiple & generic error for a lot of reasons!!
This can happen as well if you are porting Objective-C code to Swift and you move an objective C protocol to swift. If you leave off the #objc at the protocol definition and you still have Objective-C code that uses that protocol you can get this error.
The solution in that case is adding #objc to the protocol
protocol MyPortedProtocol {}
changes to
#obcj protocol MyPortedProtocol {}
Also make sure any classes that implement this protocol add #objc to the methods
I did answer in "Swift compiler segmentation fault when building"
I had this error too, and i fixed like this:
check your project and find out which files are using twice and remove one, or delete all and re-add them.
Errors in my xCode
:0: error: filename "AttributedString.swift" used twice: '/Users/.../CNJOB/CNJOB/AttributedString.swift' and '/Users/.../CNJOB/CNJOB/AttributedString.swift'
:0: note: filenames are used to distinguish private declarations with the same name
:0: error: filename "APIClient.swift" used twice: '/Users/.../CNJOB/CNJOB/APIClient.swift' and '/Users/.../CNJOB/CNJOB/APIClient.swift'
:0: note: filenames are used to distinguish private declarations with the same name
Command /Applications/Xcode 3.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc failed with exit code 1
For me it's caused by adding the swift files to different targets (today extension in my case).
I forgot to add one #end after #implementation in a .m file that had multiple classes in it. Something like:
#implementation Adjust
#end
#implementation Data //#end For this class was missing
#implementation Create
#end
I got this bug because of line
self.textView.inputAccessoryView = self.toolbarItems;
If you delete it the error will gone.
My steps:
1)
Deleted Derived data
Cleared build folder Didn't help
Copied class files to another folder as backup and commented everything in this class. Error gone.
Commented code blocks one by one until
build was success.
For me the problem was mixing Generics, Extensions, and #objc.
It turns out Xcode doesn't like having #objc inside extensions of generic classes:
class FaultyClass<T: TypeValidator>: UIControl where T.ItemType == String {
}
extension FaultyClass: UITextFieldDelegate {
func textFieldDidEndEditing(_ textField: UITextField) {
}
}
The above code gives the error #objc is not supported within extensions of generic classes. So I moved the method to the class itself but didn't delete the empty extension. This got rid of the error but when I compiled the project I got the segmentation fault.
The solution was to move UITextFieldDelegate to the class declaration.
class GoodClass: <T: TypeValidator>: UIControl, UITextFieldDelegate where T.ItemType == String {
// MARK: - TextFieldDelegate
func textFieldDidEndEditing(_ textField: UITextField) {
}
}
My problem was in methods signatures:
func setCategory(categoryId: Int?, subcategoryId: Int?) -> FilterSettings {
func changeCategory(categoryId: Int?, subcategoryId: Int?, handler: #escaping (Int) -> ()) {
I don't get why compiler cannot handle such declarations.
In my case it was because of an inappropriate inout in the function parameters. So I suggest you to look for that as well.
For me it was something similar to what #LuisCien described in this answer https://stackoverflow.com/a/42803582/4075379
I didn't have any generics or #objc tags, but it was these lines of code that were causing the segmentation fault:
public extension CGFloat {
/// Whether this number is between `other - tolerance` and `other + tolerance`
func isEqual(to other: CGFloat, tolerance: CGFloat) -> Bool {
return (other - tolerance...other + tolerance).contains(self)
}
}
i.e. an extension on a primarily Objective-C primary type?
Very luckily, I was able to delete those lines because the project wasn't using anymore. That fixed the issue.
Dumb mistake. I referred to self in a Class method:
public class func FunctionName() -> UIImage {
let bundle = Bundle.init(for: type(of: self))
...
}
I run into this problem when building some legacy code whaich was not adapted for latest Swift versions.
Segmentation fault: 11
When you open Report navigator it contains some context like:
1. Apple Swift version 5.3.2 (swiftlang-1200.0.45 clang-1200.0.32.28)
2. While evaluating request IRGenSourceFileRequest(IR Generation for file "/Users/alex/Downloads/NSURLProtocolExample-Swift_complete/NSURLProtocolExample/AppDelegate.swift")
3. While emitting IR SIL function "#$s20NSURLProtocolExample11AppDelegateC11applicationAD29didFinishLaunchingWithOptionsSbSo13UIApplicationC_So12NSDictionaryCSgtF".
for 'application(application:didFinishLaunchingWithOptions:)' (at /Users/alex/Downloads/NSURLProtocolExample-Swift_complete/NSURLProtocolExample/AppDelegate.swift:17:3)
0 swift 0x000000010b2d3615 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 37
1 swift 0x000000010b2d2615 llvm::sys::RunSignalHandlers() + 85
2 swift 0x000000010b2d3bcf SignalHandler(int) + 111
3 libsystem_platform.dylib 0x00007fff2039bd7d _sigtramp + 29
...
To solve this issue:
comment the pointed line (line 17 in AppDelegate.swift)
Build and fix all others issues
uncomment line from step 1
Swift 5 Very Easy And Smooth Solution
1- Just check your last added Extension / Code / Folder File before then this issue occur
2- Just Commit the code or save that code
3- Clean and Build & DONE :-)
Happy Coding
I ran into a similar problem when switching from beta2 to beta4.
Clean
then
Build