header-files

I've noticed that I get compilation errors if I place certain declarations in certain places in my header file. I've put comments into the code as to where I think certain things go; are they correct? @interface Level : CCNode { //Instance variables? PlayBackgroundLayer* playBGLayer; PlayUILayer* playUILayer; PlayElementLayer* playElementLayer; } //Static methods? +(void) InitLevel: (int) levelNumber; +(Level*) GetCurrentLevel; //Property declarations for instance variables? @property (nonatomic, retain) PlayBackgroundLayer* playBGLayer; @end //Static variables? Level* currentLevel;

I have two parts of my Speech Recon project with Nuance, the .h file of a module (ObjectiveC) and a ViewController (swift). I want to set up a SpeechRecognition object in my swift viewController , and listen to onBegin, onStop... and such methods. The only way to make it compile is to use nil as the delegate parameter to initialize the SpeechRecon object. Obviously this is not good because my onStart... and onFinish functions don´t trigger. I have implemented a protocol to the SKRecogniser file, and extended my ViewController class to SKReconDelegate... but if I use "self" as a delegate to

This question already has an answer here: Is there a case where including the same header twice is actually helpful? 6 answers I was reading about multiple inclusions of the same header in one file, and found an interesting statement ( link ): There are a couple of tricks with header files were you deliberately include it multiple times (this does actually provide a useful feature). I understand that those tricks are probably undesired and confusing in real-world projects (especially since people take precautions against multiple inclusions, like include guards and #pragma once ). But still,

I'm trying to call a method of a NSObject subclass I have in the let's say "main" project within a method of a XCTestCase subclass in the test project. The NSObject subclass of the main project imports the "XXX-Swift.h" header file (I'm mixing Swift and Objective-C code). All works fine when I run the main project, but when I run the tests calling an object of that subclass, I get an error saying that the Swift header file in the import is not found. I guess I'm missing some settings in the test target, but I don`t find which... what should I check? Or what should I do to solve this? Sohil R.

I'm not sure if I asked the question correctly, but let me explain. First, I read this article that explains the difference between declarations and definitions: http://www.cprogramming.com/declare_vs_define.html Second, I know from previous research that it is bad practice to define variables and functions in a header file, because during the linking phase you might have multiple definitions for the same name which will throw an error. However, how come this doesn't happen for classes? According to another SO answer ( What is the difference between a definition and a declaration? ), the