HTTPMethod.h

@interface HTTPMethod: NSString

+ (HTTPMethod *)GET;

+ (HTTPMethod *)POST;

@end

HTTPMethod.m

@interface HTTPMethod()

@property NSString *name;

@end

@implementation HTTPMethod

+ (HTTPMethod *)GET {
    return [[HTTPMethod alloc] initWithName:@"GET"];
}

+ (HTTPMethod *)POST {
    return [[HTTPMethod alloc] initWithName:@"POST"];
}

- (instancetype)initWithName:(NSString *)name {
    self = [super init];
    if (!self) return nil;
    
    _name = name;
    
    return self;
}

- (NSUInteger)length {
    return self.name.length;
}

- (unichar)characterAtIndex:(NSUInteger)index {
    return [self.name characterAtIndex:index];
}

@end