Support for grouping notifications with thread-id (#95)

* add: support for grouping notifications with thread-id

* fix: indent

Author: timakin

payload/aps.go

@@ -29,6 +29,9 @@ type APS struct {
 
 	// Mutable is used for Service Extensions introduced in iOS 10.
 	MutableContent bool
+
+	// Thread identifier to create notification groups in iOS 12 or newer.
+	ThreadID string
 }
 
 // Alert dictionary.
@@ -93,6 +96,9 @@ func (a *APS) Map() map[string]interface{} {
 	if a.MutableContent {
 		aps["mutable-content"] = 1
 	}
+	if a.ThreadID != "" {
+		aps["thread-id"] = a.ThreadID
+	}
 
 	// wrap in "aps" to form the final payload
 	return map[string]interface{}{"aps": aps}

payload/aps_test.go

@@ -91,6 +91,13 @@ func TestPayload(t *testing.T) {
 			},
 			[]byte(`{"aps":{"alert":"Change is coming","mutable-content":1}}`),
 		},
+		{
+			payload.APS{
+				Alert:    payload.Alert{Body: "Grouped notification"},
+				ThreadID: "thread-id-1",
+			},
+			[]byte(`{"aps":{"alert":"Grouped notification","thread-id":"thread-id-1"}}`),
+		},
 	}
 
 	for _, tt := range tests {