Provide Documents path related API

DocumentPathBuilder.h

#import <Foundation/Foundation.h>

// Provides Path undrer "Documents"
//
@interface DocumentPathBuilder : NSObject

@property (nonatomic, copy, readonly) NSString* documentFolder;

// Given a 'relative' filePath, return its absolute path under documents folder
//
- (NSString*) getFullPath:(NSString*)filePath;

@end

DocumentPathBuilder.m

#import "DocumentPathBuilder.h"

- (id)init
{
    self = [super init];
	if (self)
	{
		// initialize document folder property
		_documentFolder = [self getDocumentFolder];
	}

	return self;
}

- (NSString*)getDocumentFolder
{
	NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
	return paths[0];
}

- (NSString*)getFullPath:(NSString*)filePath
{
	return [self.documentFolder stringByAppendingPathComponent:filePath];
}

@end