Fix compiler warning

Cast NSUInteger to unsigned long and use %lu format specifier

http://useyourloaf.com/blog/2014/04/13/format-string-issue-using-nsinteger.html

Author: programmarchy

cocos2d-ui/CCBReader/CCBReader.m

@@ -1249,7 +1249,7 @@ - (CCNode*) readNodeGraphParent:(CCNode*)parent
         // Class was not found. Maybe it's a Swift class?
         // See http://stackoverflow.com/questions/24030814/swift-language-nsclassfromstring
         NSString *appName = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleName"];
-        NSString *classStringName = [NSString stringWithFormat:@"_TtC%d%@%d%@", appName.length, appName, className.length, className];
+        NSString *classStringName = [NSString stringWithFormat:@"_TtC%lu%@%lu%@", (unsigned long)appName.length, appName, (unsigned long)className.length, className];
         class = NSClassFromString(classStringName);
     }
     if (!class)