I am getting started with PromiseKit to prevent myself from writing functions with 10 levels of callbacks..
I installed the latest version (6.2.4) using CocoaPods, am running the latest version of xCode, imported PromiseKit in the file I am trying to get it working in, but I get really weird behavior of Xcode, resulting in several errors.
I intend to do something really basic to get started:
the function below creates filters (ProductListComponents) for categories for products in a product overview app I'm working on.
func createCategoryComponents(masterComponent: MasterComponent?) -> Promise<[ProductListComponents]> {
return Promise { seal in
//create a bunch of product category components
seal.resolve([components])
}
}
All fine here. I then try to get this:
firstly {
self.createCategoryComponents(masterComponent: masterComponent)
}.then { createdComponents in
completion.resolve(nil, createdComponents)
}
This refuses to work. firstly, when I try to type the firstly code, Xcode suggests:
firstly(execute: { () -> Guarantee<T> in
//code
})
and:
firstly(execute: { () -> Thenable in
//code
})
I have not seen this syntax in ANY of the PromiseKit documentation. It also suggests odd syntax for e.g. the .then calls. When accepting Xcode's suggestions, it obviously displays error as this is not the correct PromiseKit syntax. When ignoring Xcode's suggestion, I get this:
Obviously something is wrong here, my best guess is that something went wrong with the installation of PromiseKit. I have cleaned my project, re-installed the pod, restarted Xcode but it seems that nothing is working.
Question
Does anybody know what kind of issue I'm experiencing here and, even more importantly, how I might get it resolved?
Any helpt would be much appreciated.
According to the release notes:
then is fed the previous promise value and requires you return a promise.
done is fed the previous promise value and returns a Void promise (which is 80% of chain usage)
map is fed the previous promise value and requires you return a non-promise, ie. a value.
So, then shouldn't work here, because you need to return the promise value. If you just change then to the done it will work.
Also some suggestions.
firstly is really about visual decoration (i believe it was somewhere at PMK docs, but i can't find that right now), so, if this confuses you, try to remove that for the start;
The main feature of PMK is the chain. You definitely should write your code according to this principle;
Also, don't forget about errors. Use catch at the end of the chain for that.
Final example of your code:
firstly {
self.createCategoryComponents(masterComponent: masterComponent)
}
.done { createdComponents in
completion.resolve(nil, createdComponents)
}
.catch { error in
// don't forget about errors
}
This is what I had working with PromiseKit 4.5
api.getUserFirstName().then { name -> Void in
print(name)
}
getUserFirstName() returns a Promsise<String>. I updated to PromiseKit 6 and this now throws an error:
Cannot convert value of type '(_) -> Void' to expected argument type '(_) -> _'
This error message makes little sense to me. How do I fix this?
EDIT: So this seems to fix it, but I have little understanding as to what's happening with this:
api.getUserFirstName().compactMap { name in
print(name)
}
What's the difference now between then() and compactMap()?
In according with PromiseKit 6.0 Guide then was split into then, done and map
then is fed the previous promise value and requires you return a promise.
doneis fed the previous promise value and returns a Void promise (which is 80% of chain usage)
map is fed the previous promise value and requires you return a non-promise, ie. a value.
Why that was happend? As said developers:
With PromiseKit our then did multiple things, and we relied on Swift to infer the correct then from context. However with multiple line thens it would fail to do this, and instead of telling you that the situation was ambiguous it would invent some other error. Often the dreaded cannot convert T to AnyPromise. We have a troubleshooting guide to combat this but I believe in tools that just work, and when you spend 4 years waiting for Swift to fix the issue and Swift doesn’t fix the issue, what do you do? We chose to find a solution at the higher level.
So probably in your case needs to use done
func stackOverflowExample() {
self.getUserFirstName().done { name -> Void in
print(name)
}
}
func getUserFirstName() -> Promise<String> {
return .value("My User")
}
compactMap lets you get error transmission when nil is returned.
firstly {
URLSession.shared.dataTask(.promise, with: url)
}.compactMap {
try JSONDecoder().decode(Foo.self, with: $0.data)
}.done {
//…
}.catch {
// though probably you should return without the `catch`
}
See more info at release guide
compactMap was renamed to flatMap see discussions here
I updated to XCode 7.3 - swift 2.2 and I received a compile time error as mentioned in the title. It had no issues in swift 2.1. As per basics of swift, '?' variables can be compared to nil. I googled for possible solutions, but could not find the appropriate solution.
I think the problem was not in swift update but in ALCameraViewController update. Now it takes completion with two parameters
public typealias CameraViewCompletion = (UIImage?, PHAsset?) -> Void
So you need to change this
(image) -> Void in ...
to this
(image, asset) -> Void in ...
Actually now in your code Swift treats image as tuple of two values so also you can change all calls to image in your code with calls to image.0 that will address first closure parameter that is your UIImage?
I have Swiftache in my Swift 2 project, and after the Xcode 7 update, the following line is complaining (the error is there is no longer an extend method).
public func renderText(text: String) {
if !renderable {
return
}
_text.extend(text)
}
So _text.extend(text) is the offending line. What could I replace it with?
What did the extend method even do, originally? I can't find an equivalent because I'm not familiar with the original method back when it worked in the older version of Xcode.
Thanks!
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