Xcode keeps building on Swift 3

Question

I've converted my Swift 2.3 project to swift 3. Now the compiler doesn't throw any errors anymore but it keeps compiling. CPU is like 100% and it keeps compiling for like 50 minutes or more if you don't stop it.

Xcode keeps saying Building .. | Compiling Swift source files

In the build log it stops always on the same swift files. The swift files are just simple model classes so I don't know what the problem could be.

I had the same problem in swift 2 but that was caused by the ?? operator. I refactored the code to remove the ?? operator so it can't be this anymore.

How can I find out what slows down the compile time to endless?

My models all look the same:

class Test: InputContract { var appointmentDate: Date! var startTime: String! var endTime: String! var registerDescription: String! var subjectKey: String! var channelCode: String! var relationManagerHrId: String = "" var employeeUserCode: String = "" var smsReminderMobileNumber: String = "" var smsReminderMobileNumberSequence: String! var contactPhoneNumber: String = "" var contactPhoneNumberSequence: String! var smsReminder: Bool = false override func retrieveInputDictionary() -> NSDictionary { return ["description" : self.registerDescription, "appointmentDate" : Utils.formattedDate(self.appointmentDate), "startTime" : self.startTime, "endTime" : self.endTime, "subjectKey" : self.subjectKey, "channelCode" : self.channelCode, "smsReminder" : self.smsReminder ? "true" : "false", "relationManagerHrId" : self.relationManagerHrId, "employeeUserCode" : self.employeeUserCode, "smsReminderMobileNumber" : self.smsReminderMobileNumber, "contactPhoneNumber" : self.contactPhoneNumber, "smsReminderMobileNumberSequence" : self.smsReminderMobileNumberSequence, "contactPhoneNumberSequence" : self.contactPhoneNumberSequence ] } }

InputContract is:

protocol InputDictionaryMapper { func retrieveInputDictionary() -> NSDictionary func retrievePublicInputDictionary() -> NSDictionary } class InputContract: Model, InputDictionaryMapper { func retrieveInputDictionary() -> NSDictionary { fatalError("Each inputContract implementation must implement it's own method: \(NSStringFromClass(type(of: self)))") } func retrievePublicInputDictionary() -> NSDictionary { fatalError("Each inputContract implementation must implement it's own method: \(NSStringFromClass(type(of: self)))") } required init(json: JSON) { fatalError("init(json:) has not been implemented") } override init() { super.init() } }

And model is just a base class that has another init for json too.

When I run the analyser on the build log then all my models are taking soo long to create the NSDictionary. But Why?

1. Have you tried to clean project/restarting Xcode/etc.? 2. Have you tried to compile this Swift file in a separate project? If not, please post the contents of the Swift file on which it hangs. — fiks
– fiks, Commented Sep 28, 2016 at 8:17
It might be a problem with type inference. Could you please try storing your dictionary in a variable, e.g. let dict: [String: Any] = //...initialisation. And then return dict as NSDictionary. Also, do you really need NSDictionary? Why don't you use normal Swift Dictionary? — fiks
– fiks, Commented Sep 28, 2016 at 9:12
The first on I already tried the variable is not the solution. I also think there is a problem. But I thought NSDictionary is interchangeable with Dictionary? So you suggest I remove NSDictionary and return Dictionary<String, Any> like this? — user1007522
– user1007522, Commented Sep 28, 2016 at 9:14

user1007522 · Accepted Answer · 2016-10-10 08:29:55Z

5

So the problem was that we had a lot of dictionaries created like this:

let dict = ["key": value, "key2": value2]

If you rewrite this as

var dict: [String: Any] = [String: Any]() dict["key"] = value dict["key2"] = value2

then the compiler magically only takes 15 to 20 ms per model instead of 2000 ms per model.

You can try it yourself with the buildtime analyser app :-)

edited Oct 10, 2016 at 8:29

answered Oct 10, 2016 at 8:04

user1007522

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4 Comments

Sulthan Over a year ago

actually, the first dictionary is actually an array :) Wouldn't it be enough to define let dict: [String: Any] = .... Type inference can be slow and declaring the type should be enough.

user1007522 Over a year ago

Sorry you are right the first one was an array. I edited the code. Yes ofcourse you can drop off the [String: Any]() part. It was just to make it clear.

Jesper Over a year ago

What happens if you try let dict: [String: Any] = ["key": value, "key2": value2], ie the same thing but with a type defined?

user1007522 Over a year ago

The same happens. You really need to rewrite it the other way. That solved my endless compile but the project has almost 400 models...

Noam Hacker · Accepted Answer · 2017-03-03 07:43:08Z

I was facing the same problem after migrating the project to swift 3, but after lots of R&D I found a solution. It was taking time because of dictionaries and array created without data type.

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