enum

Enum's in Objective-C are quite simplistic in comparison with Java. Here is an example from NSProcessInfo.h. So Solaris would be 3.

enum {    /* Constants returned by -operatingSystem */
   NSWindowsNTOperatingSystem = 1,
   NSWindows95OperatingSystem,
   NSSolarisOperatingSystem,
   NSHPUXOperatingSystem,
   NSMACHOperatingSystem,
   NSSunOSOperatingSystem,
   NSOSF1OperatingSystem
};

But when you see the definition of the operatingSystem function, it actually returns integer (rather than the enum)!

- (NSUInteger)operatingSystem;

You could:

typedef enum { ... } OS;
- (OS)operatingSystem;

but as it all evaluates to int in the end no types will be checked and so it will be no help to you anyway!

Interfaces

@protocol

See also categories & posing. Seriously! :-)

@override

I cannot find an equivalent for this, which is very annoying as you never know if you have overridden a method or simply put a new one in your class with a similar signature. Xcode is a co-conspirator in this plot as it doesn't mark methods which override others, as Eclipse does (in the margin).

Javadoc

There could be a whole other blog on this. Now investigating HeaderDoc (which is built-in) and Doxygen, which is third-party but seems to have Apple approval.

final

Still looking...

Exceptions

#include "Verbose.h"

void oneway() {
   int i = 12;
   NSLog(@"oneway called");
   [NSException raise:@"Example exception" format:@"i was %d", i];
}

void anotherway() {
   NSLog(@"anotherway called");
   NSException *exception = [NSException exceptionWithName:@"foo" reason:@"bar" userInfo:nil];
   @throw exception;
}

int main (int argc, const char * argv[]) {
   NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
 
   // exception example...
   @try {
       // dealloc is called on objects on the stack on a clean-exit
       Verbose *v = [[[Verbose alloc] init] autorelease];
       // No way to @suppress this unused variable warning
       // Can turn off warnings at the compiler level but not a good idea
       oneway();
   }
   @catch(NSException *ex) {
       // No way to get a useful stack trace out - just numbered frames
       NSLog(@"exception raised '%@'", ex);
       anotherway(); // comment this out for a clean exit
   }
   @catch(NSException *ex) {
       // No warning/error/effect for the same argument name
       NSLog(@"Can't catch another '%@'", ex);
   }
   @finally {
       NSLog(@"clean up");
   }

   [pool drain];
   return 0;
}

init called
oneway called
exception raised 'i was 12'
anotherway called
clean up
*** Terminating app due to uncaught exception 'foo', reason: 'bar'
Stack: (
    2488033451,
    2523823675
)

InstanceOf

int main (int argc, const char * argv[]) {
 NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

 // id is like (void*) in C++ or Object in Java
 //id something = nil; // Pointers not set to nil by default
 id something = [[NSArray alloc] init];
 if ((something != nil) && [something isKindOfClass:[NSArray class]]) {
     // Without the !=nil check the program will SEGV with something==nil
     NSLog(@"It's an array!");
 }

 [pool drain];
 return 0;
}

It's an array!