upperlacon upperlacon - 1 year ago 105
Swift Question

swift_unknownRelease Crash - SwiftHTTP

I have suddenly started observing the below crash on a new update to one of my apps. It seems to be happening quite frequently, and is confusing as I have made no changes to this section of the code in the last 6 months. I did wonder if this (EXC_BAD_ACCESS on returning a throwing Dictionary) Swift radar bug might be relevant, if the crash is due to forming the params dictionary for this request.

This build was created using Swift 2.2 and Xcode 7.3. SwiftHTTP is v1.0.4. I see crashes with the production binary on iOS 8.3.0, 9.3.0 and 9.3.1. This issue is most prevalent (87%) on iPhone 6, 6 Plus and 6s. I have tried to reproduce this issue using Xcode Zombies (as per here) but it did not show any

message sent to deallocated instance
messages in the console.

The crash occurs in performing a PUT update in a helper class I have for the SwiftHTTP library.



Stack Trace

Thread : Crashed: com.apple.main-thread
0 libswiftCore.dylib 0x100d6d8f8 swift_unknownRelease + 24
1 SwiftHTTP 0x100b07298 _TTSf4g_n___TTSg5Ps9AnyObject____TFE9SwiftHTTPSa11createPairsfGSqSS_GSaVS_8HTTPPair_ + 700
2 SwiftHTTP 0x100b002f4 _TFE9SwiftHTTPVs10Dictionary11createPairsfGSqSS_GSaVS_8HTTPPair_ + 2000
3 SwiftHTTP 0x100b00f90 _TTWu0_Rxs8HashablerGVs10Dictionaryxq__9SwiftHTTP21HTTPParameterProtocolS1_FS2_11createPairsfGSqSS_GSaVS1_8HTTPPair_ + 112
4 SwiftHTTP 0x100b0178c _TFE9SwiftHTTPCSo19NSMutableURLRequest16appendParametersfzPS_21HTTPParameterProtocol_T_ + 396
5 SwiftHTTP 0x100af14a4 _TTWV9SwiftHTTP23HTTPParameterSerializerS_21HTTPSerializeProtocolS_FS1_9serializefzTCSo19NSMutableURLRequest10parametersPS_21HTTPParameterProtocol__T_ + 40
6 SwiftHTTP 0x100af8ccc _TTSf4gs_n_n_g_n_d___TZFC9SwiftHTTP4HTTP3NewfzTSS6methodOS_8HTTPVerb10parametersGSqPS_21HTTPParameterProtocol__7headersGSqGVs10DictionarySSSS__17requestSerializerPS_21HTTPSerializeProtocol__S0_ + 624
7 SwiftHTTP 0x100af5758 _TZFC9SwiftHTTP4HTTP3PUTfzTSS10parametersGSqPS_21HTTPParameterProtocol__7headersGSqGVs10DictionarySSSS__17requestSerializerPS_21HTTPSerializeProtocol__S0_ + 76
8 MyApp 0x1001274c0 SwiftHTTPUtilities.PUT(String, auth : String, params : [String : AnyObject]?, model : String, mode : APIUtilities.ApiRequestType, object : AnyObject?) -> () (SwiftHTTPUtilities.swift:52)
9 MyApp 0x100154e90 APIUtilities.(apiRequest(String, mode : APIUtilities.ApiRequestType, object : AnyObject?) -> ()).(closure #3) (APIUtilities.swift:76)
10 MyApp 0x100152f70 partial apply for APIUtilities.(apiRequest(String, mode : APIUtilities.ApiRequestType, object : AnyObject?) -> ()).(closure #3) (APIUtilities.swift)
11 libdispatch.dylib 0x18364d4bc _dispatch_call_block_and_release + 24
12 libdispatch.dylib 0x18364d47c _dispatch_client_callout + 16
13 libdispatch.dylib 0x183652b84 _dispatch_main_queue_callback_4CF + 1844
14 CoreFoundation 0x183bb8dd8 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 12
15 CoreFoundation 0x183bb6c40 __CFRunLoopRun + 1628
16 CoreFoundation 0x183ae0d10 CFRunLoopRunSpecific + 384
17 GraphicsServices 0x1853c8088 GSEventRunModal + 180
18 UIKit 0x188db5f70 UIApplicationMain + 204
19 MyApp 0x10026d508 main (AppDelegate.swift:25)
20 libdispatch.dylib 0x18367e8b8 (Missing)

SwiftHTTPUtilities (which is a helper class to interact with the open source library SwiftHTTP)

func PUT(apiPath: String, auth: String, params: Dictionary<String,AnyObject>?,model: String, mode: APIUtilities.ApiRequestType, object: AnyObject?) {
do {
let opt = try HTTP.PUT("\(apiPath)", parameters: params, headers: ["*removed*"])
opt.start { response in
if let err = response.error {
// print("error: \(err.localizedDescription)")
self.delegate?.didGetServerResponse(false, response: nil, error: response.error, model: model, mode: mode, object: object)
return //also notify app of failure as needed
// print("opt finished: \(response.description)")
//print("data is: \(response.data)") access the response of the data with response.data

self.delegate?.didGetServerResponse(true, response: response.data, error: nil, model: model, mode: mode, object: object)
} catch let error {
// print("got an error creating the request: \(error)")
self.delegate?.didGetServerResponse(false, response: nil, error: nil, model: model, mode: mode, object: object)


Answer Source

This issue was due to SwiftHTTP defaulting to HTTPSerialisation. The below line is how to specify JSON serialisation, which fixed the bug for me.

let opt = try HTTP.New("\(apiPath)", method: .PUT, parameters: params, headers: ["Authorization": "edit"], requestSerializer: JSONParameterSerializer())