smcFanControl/Classes/NSFileManager+DirectoryLocations.m

//
//  NSFileManager+DirectoryLocations.m
//
//  Created by Matt Gallagher on 06 May 2010
//
//  This software is provided 'as-is', without any express or implied
//  warranty. In no event will the authors be held liable for any damages
//  arising from the use of this software. Permission is granted to anyone to
//  use this software for any purpose, including commercial applications, and to
//  alter it and redistribute it freely, subject to the following restrictions:
//
//  1. The origin of this software must not be misrepresented; you must not
//     claim that you wrote the original software. If you use this software
//     in a product, an acknowledgment in the product documentation would be
//     appreciated but is not required.
//  2. Altered source versions must be plainly marked as such, and must not be
//     misrepresented as being the original software.
//  3. This notice may not be removed or altered from any source
//     distribution.
//

#import "NSFileManager+DirectoryLocations.h"

enum
{
	DirectoryLocationErrorNoPathFound,
	DirectoryLocationErrorFileExistsAtLocation
};
	
NSString * const DirectoryLocationDomain = @"DirectoryLocationDomain";

@implementation NSFileManager (DirectoryLocations)


/*!  Method to tie together the steps of:
	1) Locate a standard directory by search path and domain mask
    2) Select the first path in the results
 	3) Append a subdirectory to that path
	4) Create the directory and intermediate directories if needed
	5) Handle errors by emitting a proper NSError object

* \pararm searchPathDirectory - the search path passed to NSSearchPathForDirectoriesInDomains
* \pararm domainMask - the domain mask passed to NSSearchPathForDirectoriesInDomains
* \pararm appendComponent - the subdirectory appended
* \pararm errorOut - any error from file operations

* \returns returns the path to the directory (if path found and exists), nil otherwise
*/
- (NSString *)findOrCreateDirectory:(NSSearchPathDirectory)searchPathDirectory
	inDomain:(NSSearchPathDomainMask)domainMask
	appendPathComponent:(NSString *)appendComponent
	error:(NSError **)errorOut
{
    // Declare an NSError first, so we don't need to check errorOut again and again
    NSError *error;
    
    if (errorOut) {
        error = *errorOut;
    }
    else {
        error = nil;
    }

	//
	// Search for the path
	//
	NSArray* paths = NSSearchPathForDirectoriesInDomains(searchPathDirectory,domainMask,YES);
    
	if ([paths count] == 0)
	{
        NSDictionary *userInfo = @{NSLocalizedDescriptionKey: NSLocalizedStringFromTable(@"No path found for directory in domain.",@"Errors",nil),
                                    @"NSSearchPathDirectory":@(searchPathDirectory),
                                    @"NSSearchPathDomainMask":@(domainMask)};
				
        error = [NSError errorWithDomain:DirectoryLocationDomain
                                        code:DirectoryLocationErrorNoPathFound
                                    userInfo:userInfo];
		return nil;
	}
	
	//
	// Normally only need the first path returned
	//
	NSString *resolvedPath = paths[0];

	//
	// Append the extra path component
	//
	if (appendComponent)
	{
		resolvedPath = [resolvedPath stringByAppendingPathComponent:appendComponent];
	}
	
	//
	// Create the path if it doesn't exist
	//
    
    
	if ([self createDirectoryAtPath:resolvedPath withIntermediateDirectories:YES
                          attributes:nil error:&error])
        return resolvedPath;
    else
        return nil;
}


/*! applicationSupportDirectory

* \returns The path to the applicationSupportDirectory (creating it if it doesn't exist).
*/
- (NSString *)applicationSupportDirectory
{
	NSString *executableName = [[NSBundle mainBundle] infoDictionary][@"CFBundleExecutable"];
    
	NSError *error = nil;
    
	NSString *result = [self findOrCreateDirectory:NSApplicationSupportDirectory
                                          inDomain:NSUserDomainMask
                               appendPathComponent:executableName
                                             error:&error];
	if (!result)
	{
		NSLog(@"Unable to find or create application support directory:\n%@", error);
	}
	return result;
}

@end