Fixed parsing of the rate limit error response

Cherry-picked from f7a543a.

Author: simonseyer

MapboxGeocoder/MBGeocoder.swift

@@ -282,23 +282,22 @@ public class Geocoder: NSObject {
     /**
      Returns an error that supplements the given underlying error with additional information from the an HTTP response’s body or headers.
      */
-    private static func descriptiveError(json: JSONDictionary, response: NSURLResponse?, underlyingError error: NSError?) -> NSError {
+    static func descriptiveError(json: JSONDictionary, response: NSURLResponse?, underlyingError error: NSError?) -> NSError {
         var userInfo = error?.userInfo ?? [:]
         if let response = response as? NSHTTPURLResponse {
             var failureReason: String? = nil
             var recoverySuggestion: String? = nil
             switch response.statusCode {
             case 429:
-                if let timeInterval = response.allHeaderFields["x-rate-limit-interval"] as? NSTimeInterval, maximumCountOfRequests = response.allHeaderFields["x-rate-limit-limit"] as? UInt {
+                if let timeInterval = response.rateLimitInterval, let maximumCountOfRequests = response.rateLimit {
                     let intervalFormatter = NSDateComponentsFormatter()
                     intervalFormatter.unitsStyle = .Full
-                    let formattedInterval = intervalFormatter.stringFromTimeInterval(timeInterval)
+                    let formattedInterval = intervalFormatter.stringFromTimeInterval(timeInterval) ?? "? minutes"
                     let formattedCount = NSNumberFormatter.localizedStringFromNumber(maximumCountOfRequests, numberStyle: .DecimalStyle)
                     failureReason = "More than \(formattedCount) requests have been made with this access token within a period of \(formattedInterval)."
                 }
-                if let rolloverTimestamp = response.allHeaderFields["x-rate-limit-reset"] as? Double {
-                    let date = NSDate(timeIntervalSince1970: rolloverTimestamp)
-                    let formattedDate = NSDateFormatter.localizedStringFromDate(date, dateStyle: .LongStyle, timeStyle: .FullStyle)
+                if let rolloverTime = response.rateLimitResetTime {
+                    let formattedDate = NSDateFormatter.localizedStringFromDate(rolloverTime, dateStyle: .LongStyle, timeStyle: .FullStyle)
                     recoverySuggestion = "Wait until \(formattedDate) before retrying."
                 }
             default:
@@ -311,3 +310,35 @@ public class Geocoder: NSObject {
         return NSError(domain: error?.domain ?? MBGeocoderErrorDomain, code: error?.code ?? -1, userInfo: userInfo)
     }
 }
+
+extension NSHTTPURLResponse {
+    
+    @nonobjc static let rateLimitIntervalHeaderKey = "X-Rate-Limit-Interval"
+    @nonobjc static let rateLimitLimitHeaderKey = "X-Rate-Limit-Limit"
+    @nonobjc static let rateLimitResetHeaderKey = "X-Rate-Limit-Reset"
+    
+    var rateLimit: UInt? {
+        guard let limit = allHeaderFields[NSHTTPURLResponse.rateLimitLimitHeaderKey] as? String else {
+            return nil
+        }
+        return UInt(limit)
+    }
+    
+    var rateLimitInterval: NSTimeInterval? {
+        guard let interval = allHeaderFields[NSHTTPURLResponse.rateLimitIntervalHeaderKey] as? String else {
+            return nil
+        }
+        return NSTimeInterval(interval)
+    }
+    
+    var rateLimitResetTime: NSDate? {
+        guard let resetTime = allHeaderFields[NSHTTPURLResponse.rateLimitResetHeaderKey] as? String else {
+            return nil
+        }
+        guard let resetTimeNumber = Double(resetTime) else {
+            return nil;
+        }
+        return NSDate(timeIntervalSince1970: resetTimeNumber)
+    }
+
+}

MapboxGeocoderTests/GeocoderTests.swift

@@ -5,6 +5,12 @@ import OHHTTPStubs
 let BogusToken = "pk.feedCafeDadeDeadBeef-BadeBede.FadeCafeDadeDeed-BadeBede"
 
 class GeocoderTests: XCTestCase {
+    
+    override func setUp() {
+        // Make sure tests run in all time zones
+        NSTimeZone.setDefaultTimeZone(NSTimeZone(forSecondsFromGMT: 0))
+    }
+    
     override func tearDown() {
         OHHTTPStubs.removeAllStubs()
         super.tearDown()
@@ -15,4 +21,19 @@ class GeocoderTests: XCTestCase {
         XCTAssertEqual(geocoder.accessToken, BogusToken)
         XCTAssertEqual(geocoder.apiEndpoint.absoluteString, "https://api.mapbox.com")
     }
+    
+    func testRateLimitErrorParsing() {
+        let json = ["message" : "Hit rate limit"]
+        
+        let url = NSURL(string: "https://api.mapbox.com")!
+        let headerFields = ["X-Rate-Limit-Interval" : "60", "X-Rate-Limit-Limit" : "600", "X-Rate-Limit-Reset" : "1479460584"]
+        let response = NSHTTPURLResponse(URL: url, statusCode: 429, HTTPVersion: nil, headerFields: headerFields)
+        
+        let error: NSError? = nil
+        
+        let resultError = Geocoder.descriptiveError(json, response: response, underlyingError: error)
+        
+        XCTAssertEqual(resultError.localizedFailureReason, "More than 600 requests have been made with this access token within a period of 1 minute.")
+        XCTAssertEqual(resultError.localizedRecoverySuggestion, "Wait until November 18, 2016 at 9:16:24 AM GMT before retrying.")
+    }
 }