don't execute operation block if it was canceled before (#429)

don't add prams if they are empty

Author: dejan2k

Leanplum-SDK/Classes/Managers/Networking/LPRequest.m

@@ -110,7 +110,9 @@ - (NSMutableDictionary *)createArgsDictionary
     if ([LPAPIConfig sharedConfig].token) {
         args[LP_PARAM_TOKEN] = [LPAPIConfig sharedConfig].token;
     }
-    [args addEntriesFromDictionary:self.params];
+    if (self.params && self.params.count > 0) {
+        [args addEntriesFromDictionary:self.params];
+    }
 
     // remove keys that are empty
     [args removeObjectForKey:@""];

Leanplum-SDK/Classes/Managers/Networking/LPRequestSender.m

@@ -132,9 +132,16 @@ - (void)saveRequest:(LPRequest *)request
     RETURN_IF_TEST_MODE;
     if (!request.sent) {
         request.sent = YES;
-
+        
+        NSBlockOperation *saveRequestOperation = [NSBlockOperation new];
+        __weak NSBlockOperation *weakOperation = saveRequestOperation;
+        
         void (^operationBlock)(void) = ^void() {
             LP_TRY
+            if ([weakOperation isCancelled]) {
+                return;
+            }
+            
             NSString *uuid = [LPRequestUUIDHelper loadUUID];
             NSInteger count = [LPEventDataManager count];
             if (!uuid || count % LP_MAX_EVENTS_PER_API_CALL == 0) {
@@ -152,7 +159,8 @@ - (void)saveRequest:(LPRequest *)request
             LP_END_TRY
         };
 
-        [[LPOperationQueue serialQueue] addOperationWithBlock:operationBlock];
+        [saveRequestOperation addExecutionBlock:operationBlock];
+        [[LPOperationQueue serialQueue] addOperation:saveRequestOperation];
     }
 
     [self.countAggregator incrementCount:@"send_eventually_lp"];