動的型検査付きNSArray/NSDictionary

NSCollection+TypeSafe.h

//
//  NSCollection+TypeSafe.h
//

#import <Foundation/Foundation.h>

#define TYPESAFE_ARRAY(classname) \
	@interface NSArray (TypeSafe ## classname) \
	- (classname *)get ## classname:(int)index; \
	- (classname *)get ## classname:(int)index none:(classname *)none; \
	@end \
	@implementation NSArray (TypeSafe ## classname) \
	- (classname *)get ## classname:(id)index \
	{ \
		return [self get ## classname:index none:nil]; \
	} \
	- (classname *)get ## classname:(int)index none:(classname *)none \
	{ \
		NSObject *object = [self objectAtIndex:index]; \
		if ([object isKindOfClass:[classname class]]) { \
			return object; \
		} \
		return none; \
	} \
	@end

#define TYPESAFE_DICTIONARY(classname) \
	@interface NSDictionary (TypeSafe ## classname) \
	- (classname *)get ## classname:(id)key; \
	- (classname *)get ## classname:(id)key none:(classname *)none; \
	@end \
	@implementation NSDictionary (TypeSafe ## classname) \
	- (classname *)get ## classname:(id)key \
	{ \
		return [self get ## classname:key none:nil]; \
	} \
	- (classname *)get ## classname:(id)key none:(classname *)none \
	{ \
		classname *object = [self objectForKey:key]; \
		if ([object isKindOfClass:[classname class]]) { \
			return object; \
		} \
		return none; \
	} \
	@end

NSCollection+TypeSafe.m

// 使い方のサンプル

#import "NSCollection+TypeSafe.h"
TYPESAFE_ARRAY(NSString)
TYPESAFE_ARRAY(NSNumber)

@interface Hoge : NSObject

@end

@implementation Hoge

- (void)hoge
{
	NSArray *array = [NSArray arrayWithObjects:@"a", @"b", @"c", nil];
	NSLog(@"0: %@", [array getNSString:0]); // => a
	NSLog(@"1: %@", [array getNSNumber:1]); // => (null)
}

@end