Dictionary Types Helper

DictionaryTypesHelper.m

//  DictionaryTypesHelper.h
#import <Foundation/Foundation.h>

@interface NSDictionary (NSDictionary_DictionaryTypesHelper)

- (NSArray*)arrayForKey:(id)key;
- (NSDictionary*)dictionaryForKey:(id)key;
- (NSString*)stringForKey:(id)key;
- (NSNumber*)numberForKey:(id)key;
- (NSData*)dataForKey:(id)key;
- (BOOL)boolForKey:(id)key;
- (float)floatForKey:(id)key;
- (int)intForKey:(id)key;
- (double)doubleForKey:(id)key;

@end

@interface NSObject (NSObject_WhatIsHelper)

- (BOOL)isDict;
- (BOOL)isArray;
- (BOOL)isString;
- (BOOL)isNull;
- (BOOL)isNumber;
- (BOOL)isData;

@end

// ---

//  DictionaryTypesHelper.m
#import "DictionaryTypesHelper.h"

// Say we have a dictionary full of these types
// NSDictionary
// NSArray
// NSString
// NSNumber
// NSNull
// We need to ensure they are the correct types when pulling them out
// These functions return the values if correct, coax them correctly
// if possible, or return nil (not nsnull) if impossible

@implementation NSDictionary (NSDictionary_DictionaryTypesHelper)

// These ones don't attempt to coax - you're either an X or you're nil.
- (NSArray*)arrayForKey:(id)key {
	id o = [self objectForKey:key];
	return [o isArray] ? o : nil;
}

- (NSDictionary*)dictionaryForKey:(id)key {
	id o = [self objectForKey:key];
	return [o isDict] ? o : nil;
}

- (NSData*)dataForKey:(id)key {
	id o = [self objectForKey:key];
	return [o isData] ? o : nil;
}

// These ones try to coax, but return nil if they are not in the dictionary or are nsnulls
- (NSString*)stringForKey:(id)key {
	id o = [self objectForKey:key];
	if ([o isString]) return o;
	if (!o || [o isNull]) return nil;
	return [o description];
}

- (NSNumber*)numberForKey:(id)key {
	id o = [self objectForKey:key];
	if ([o isNumber]) return o;
	if (!o || [o isNull]) return nil;
	return [NSNumber numberWithLongLong:[o description].longLongValue];
}

// These ones simply return zero if they can't figure it out
- (BOOL)boolForKey:(id)key {
	id o = [self objectForKey:key];
	if ([o isNumber]) return [o boolValue];
	return [o description].boolValue;
}

- (float)floatForKey:(id)key {
	id o = [self objectForKey:key];
	if ([o isNumber]) return [o floatValue];
	return [o description].floatValue;
}

- (int)intForKey:(id)key {
	id o = [self objectForKey:key];
	if ([o isNumber]) return [o intValue];
	return [o description].intValue;
}

- (double)doubleForKey:(id)key {
	id o = [self objectForKey:key];
	if ([o isNumber]) return [o doubleValue];
	return [o description].doubleValue;
}

@end


@implementation NSObject (NSObject_WhatIsHelper)

- (BOOL)isDict {
	return [self isKindOfClass:[NSDictionary class]];
}
- (BOOL)isArray {
	return [self isKindOfClass:[NSArray class]];
}
- (BOOL)isString {
	return [self isKindOfClass:[NSString class]];
}
- (BOOL)isNumber {
	return [self isKindOfClass:[NSNumber class]];
}
- (BOOL)isNull {
	return self==[NSNull null];
}
- (BOOL)isData {
	return [self isKindOfClass:[NSData class]];
}

@end