Memory Management Objective-C - objective-c

Question

I don't understand why memory consumption increases and never gets released (the project is using ARC) when performing the following operations in my program (please bear with me, I'm at a basic level with plain C):
Simplified: somewhere in my program (AppDelegate for example) I call a macro which basically is a C function with variable parameters which calls other C functions that are returning some NSStrings.
These are defined and implemented in an Objective-C style class and are used together with a singleton object.
Header:
#interface MyClass : NSObject
#end
void func_1(aTypeDef paramType, NSString *input, ...);
void* func_2(NSString *arg1, NSString *arg2, NSString *arg3);
NSString* string_func_1 (void);
NSString* string_func_2 (int anInt);
NSString* string_func_3 (const char *aString);
#define F2_MACRO func_2( \
string_func_1(), \
string_func_2(anINT), \
string_func_3(aSTRING), \
)
#define F1_MACRO(input, ...) func_1(A_TYPE, input, ##__VA_ARGS__, F2_MACRO)
Implementation:
#import "MyClass.h"
static NSString *STRING_1;
static NSString *STRING_2;
static NSString *STRING_3;
#implementation MyClass
void func_1(aTypeDef paramType, NSString *input, ...) {
va_list args;
va_start(args, input);
NSString *output = [[NSString alloc] initWithFormat:input arguments:args];
fputs([output UTF8String], stdout);
va_end(args);
}
void* func_2(NSString *arg1, NSString *arg2, NSString *arg3) {
STRING_1 = arg1;
STRING_2 = arg2;
STRING_3 = arg3;
return NULL;
}
NSString* string_func_1 (void) {
return [NSString stringWithFormat:#"aString"];
}
NSString* string_func_2 (int anInt) {
return [NSString stringWithFormat:#"%d",anInt];
}
NSString* string_func_3 (const char *aString) {
return [NSString stringWithUTF8String:aString];
}
#end
Every time I call the F1_MACRO() in another Objective-C class like AppDelegate memory usage increases every time the string_func_1, string_func_2, string_func_3 return.
I'm sure that my logic and implementation are flawed and I'll appreciate any help.

Answer 1

func_1() is creating a non-autoreleased object.
• If you are using Automatic Reference Counting (ARC), not autoreleasing the object is fine, however it can still lead to apparent memory accretion. Specifically, if you don't have an explicitly #autoreleasepool{} or are not running an event loop on the thread that is calling that function, then the autoreleased object will never be released.
• If you aren't using ARC, then that is a straight up leak. Add [output release]; at the end of the func_1() function.