NSString+NSUserDefaults.h

#import <Foundation/Foundation.h>

@interface NSString (NSUserDefaults)
@property BOOL defaultsBool;
@property NSInteger defaultsInteger;
@property float defaultsFloat;
@property double defaultsDouble;
@property id defaultsObject;
@property NSData *defaultsData;
@property NSString *defaultsString;
@property NSURL *defaultsURL;
@property NSArray *defaultsArray;
@property NSDictionary *defaultsDictionary;
@end

NSString+NSUserDefaults.m

#import "NSString+NSUserDefaults.h"

#import "user_defaults.h"

@implementation NSString (NSUserDefaults)

- (BOOL)defaultsBool
{
    return NSUserDefaultsReadBool(self);
}

- (void)setDefaultsBool:(BOOL)defaultsBool
{
    NSUserDefaultsWriteBool(self, defaultsBool);
}

- (NSInteger)defaultsInteger
{
    return NSUserDefaultsReadInteger(self);
}

- (void)setDefaultsInteger:(NSInteger)defaultsInteger
{
    NSUserDefaultsWriteInteger(self, defaultsInteger);
}

- (float)defaultsFloat
{
    return NSUserDefaultsReadFloat(self);
}

- (void)setDefaultsFloat:(float)defaultsFloat
{
    NSUserDefaultsWriteFloat(self, defaultsFloat);
}

- (double)defaultsDouble
{
    return NSUserDefaultsReadDouble(self);
}

- (void)setDefaultsDouble:(double)defaultsDouble
{
    NSUserDefaultsWriteDouble(self, defaultsDouble);
}

- (id)defaultsObject
{
    return NSUserDefaultsReadObject(self);
}

- (void)setDefaultsObject:(id)defaultsObject
{
    NSUserDefaultsWriteObject(self, defaultsObject);
}

- (NSData *)defaultsData
{
    id obj = self.defaultsObject;
    return [obj isKindOfClass:[NSData class]] ? obj : nil;
}

- (void)setDefaultsData:(NSData *)defaultsData
{
    self.defaultsObject = defaultsData;
}

- (NSString *)defaultsString
{
    id obj = self.defaultsObject;
    return [obj isKindOfClass:[NSString class]] ? obj : nil;
}

- (void)setDefaultsString:(NSString *)defaultsString
{
    self.defaultsObject = defaultsString;
}

- (NSURL *)defaultsURL
{
    return NSUserDefaultsReadURL(self);
}

- (void)setDefaultsURL:(NSURL *)defaultsURL
{
    NSUserDefaultsWriteURL(self, defaultsURL);
}

- (NSArray *)defaultsArray
{
    id obj = self.defaultsObject;
    return [obj isKindOfClass:[NSArray class]] ? obj : nil;
}

- (void)setDefaultsArray:(NSArray *)defaultsArray
{
    self.defaultsObject = defaultsArray;
}

- (NSDictionary *)defaultsDictionary
{
    id obj = self.defaultsObject;
    return [obj isKindOfClass:[NSDictionary class]] ? obj : nil;
}

- (void)setDefaultsDictionary:(NSDictionary *)defaultsDictionary
{
    self.defaultsObject = defaultsDictionary;
}

@end

user_defaults.h

#ifndef user_defaults_h
#define user_defaults_h

#import <Foundation/Foundation.h>

#define NSUserDefaults_Write(aKey, anObject, method) \
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];\
    if (anObject) {\
        [defaults method:anObject forKey:aKey];\
    } else {\
        [defaults removeObjectForKey:aKey];\
    }\
    [defaults synchronize]

#define NSUserDefaults_Read(aKey, method) \
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];\
    return [defaults method:aKey]



static inline void NSUserDefaultsWriteObject(id aKey, id anObject)
{
    NSUserDefaults_Write(aKey, anObject, setObject);
}

static inline void NSUserDefaultsWriteURL(id aKey, NSURL *anObject)
{
    NSUserDefaults_Write(aKey, anObject, setURL);
}

static inline void NSUserDefaultsWriteBool(id aKey, BOOL anObject)
{
    NSUserDefaults_Write(aKey, anObject, setBool);
}

static inline void NSUserDefaultsWriteInteger(id aKey, NSInteger anObject)
{
    NSUserDefaults_Write(aKey, anObject, setInteger);
}

static inline void NSUserDefaultsWriteFloat(id aKey, float anObject)
{
    NSUserDefaults_Write(aKey, anObject, setFloat);
}

static inline void NSUserDefaultsWriteDouble(id aKey, double anObject)
{
    NSUserDefaults_Write(aKey, anObject, setDouble);
}

static inline id NSUserDefaultsReadObject(id aKey)
{
    NSUserDefaults_Read(aKey, objectForKey);
}

static inline id NSUserDefaultsReadURL(id aKey)
{
    NSUserDefaults_Read(aKey, URLForKey);
}

static inline BOOL NSUserDefaultsReadBool(id aKey)
{
    NSUserDefaults_Read(aKey, boolForKey);
}

static inline NSInteger NSUserDefaultsReadInteger(id aKey)
{
    NSUserDefaults_Read(aKey, integerForKey);
}

static inline float NSUserDefaultsReadFloat(id aKey)
{
    NSUserDefaults_Read(aKey, floatForKey);
}

static inline double NSUserDefaultsReadDouble(id aKey)
{
    NSUserDefaults_Read(aKey, doubleForKey);
}

#endif