Question

I recently started to wonder why we usually import .h files instead of .m files in Objective C.

#import ClassName.h

Is there any benefit on importing .h files over .m files?

Answer 1

The .m file is meant to be private, while the .h file is meant to be imported and used by other classes. For example, a small section of your .h file might look like this:

@property (nonatomic) NSInteger myPublicInteger;

- (void)myPublicMethod;

Your .m file on the other hand might look like this:

#import "MyClassNameHere.h"

@interface MyClassNameHere()
@property (nonatomic) NSInteger myPrivateInteger;
- (void)myPrivateMethod
@end

@implementation MyClassNameHere
@synthesize myPrivateInteger, myPublicInteger;

- (void)myPrivateMethod
{
    //some code here
}

- (void)myPublicMethod
{
    //some code here
}

Classes that import your .h file and create an instance of your class will be able to directly access myPublicInteger and send messages to myPublicMethod. However, they will not have any access or knowledge of myPrivateInteger or myPrivateMethod.