ios: fix compilation warnings

ios/sdk/src/dropbox/Dropbox.m

         [DBClientsManager authorizeFromController:[UIApplication sharedApplication]
                                        controller:[[self class] topMostController]
                                           openURL:^(NSURL *url) {
-                                              [[UIApplication sharedApplication] openURL:url];
+                                              [[UIApplication sharedApplication] openURL:url options:@{} completionHandler:nil];
                                           }];
     });
 }
         } else {
             NSString *msg;
             if ([authResult isError]) {
-                msg = [NSString stringWithFormat:@"%@, error type: %ld",[authResult errorDescription], [authResult errorType]];
+                msg = [NSString stringWithFormat:@"%@, error type: %zd",[authResult errorDescription], [authResult errorType]];
             } else {
                 msg = @"OAuth canceled!";
             }