Added setCurrency method (#140)

* Added setCurrency method

Author: kurtsergey

README.md

@@ -360,6 +360,16 @@ Sets tracker sampling rate.
 tracker.setSamplingRate(50);
 ```
 
+### setCurrency(currencyCode)
+
+* **currencyCode (required):** String, ISO 4217 currency code
+
+Sets tracker currency property, see [Currency Codes](https://developers.google.com/analytics/devguides/platform/features/currencies).
+
+```javascript
+tracker.setCurrency('EUR');
+```
+
 ## GoogleAnalyticsSettings API
 
 Settings are applied across all trackers.

android/src/main/java/com/idehub/GoogleAnalyticsBridge/GoogleAnalyticsBridge.java

@@ -427,6 +427,16 @@ public void setAppVersion(String trackerId, String appVersion){
         }
     }
 
+    @ReactMethod
+    public void setCurrency(String trackerId, String currencyCode)
+    {
+        Tracker tracker = getTracker(trackerId);
+
+        if (tracker != null) {
+            tracker.set("&cu", currencyCode);
+        }
+    }
+
     @ReactMethod
     public void trackCampaignFromUrl(String trackerId, String urlString){
         Tracker tracker = getTracker(trackerId);

ios/RCTGoogleAnalyticsBridge/RCTGoogleAnalyticsBridge/RCTGoogleAnalyticsBridge.m

@@ -310,6 +310,12 @@ - (NSDictionary *)constantsToExport
     [tracker set:kGAIAppVersion value:appVersion];
 }
 
+RCT_EXPORT_METHOD(setCurrency:(NSString *)trackerId currencyCode:(NSString *)currencyCode)
+{
+    id<GAITracker> tracker = [[GAI sharedInstance] trackerWithTrackingId:trackerId];
+    [tracker set:kGAICurrencyCode
+         value:currencyCode];
+}
 
 RCT_EXPORT_METHOD(trackCampaignFromUrl:(NSString *)trackerId urlString:(NSString *)urlString)
 {

src/GoogleAnalyticsBackwardsCompability.js

@@ -108,4 +108,8 @@ export class GoogleAnalyticsBackwardsCompability {
   setSamplingRate(sampleRatio) {
     this.tracker.setSamplingRate(sampleRatio);
   }
+
+  setCurrency(currencyCode) {
+    this.tracker.setCurrency(currencyCode);
+  }
 }

src/GoogleAnalyticsTracker.js

@@ -217,4 +217,12 @@ export class GoogleAnalyticsTracker {
   setSamplingRate(sampleRatio) {
     GoogleAnalyticsBridge.setSamplingRate(this.id, sampleRatio);
   }
+  
+  /**
+   * Sets the currency for tracking.
+   * @param {String} currencyCode The currency ISO 4217 code
+   */
+  setCurrency(currencyCode) {
+    GoogleAnalyticsBridge.setCurrency(this.id, currencyCode);
+  }
 }