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)

//
// findOrCreateDirectory:inDomain:appendPathComponent:error:
//
// 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
//
// Parameters:
//    searchPathDirectory - the search path passed to NSSearchPathForDirectoriesInDomains
//    domainMask - the domain mask passed to NSSearchPathForDirectoriesInDomains
//    appendComponent - the subdirectory appended
//    errorOut - any error from file operations
//
// 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
{
    //
    // Search for the path
    //
    NSArray* paths = NSSearchPathForDirectoriesInDomains(searchPathDirectory, domainMask, YES);
    
    if (paths.count == 0) {
        if (errorOut) {
            NSDictionary *userInfo = @{
                                       NSLocalizedDescriptionKey: NSLocalizedStringFromTable(@"No path found for directory in domain.",
                                                                                             @"Errors",
                                                                                             nil),
                                       @"NSSearchPathDirectory": @(searchPathDirectory),
                                       @"NSSearchPathDomainMask": @(domainMask)};
            *errorOut = [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
    //
    NSError *error = nil;
    BOOL success = [self createDirectoryAtPath:resolvedPath
                   withIntermediateDirectories:YES
                                    attributes:nil
                                         error:&error];
    if (!success) {
        if (errorOut) {
            *errorOut = error;
        }
        return nil;
    }
    
    //
    // If we've made it this far, we have a success
    //
    if (errorOut) {
        *errorOut = nil;
    }
    return resolvedPath;
}

//
// applicationSupportDirectory
//
// Returns the path to the applicationSupportDirectory (creating it if it doesn't
// exist).
//
- (NSString *)applicationSupportDirectory
{
    NSString *executableName = [NSBundle mainBundle].infoDictionary[@"CFBundleExecutable"];

    NSString *dirName = [executableName stringByAppendingString:GIA_DEBUG_PROFILE];

    NSError *error;
    NSString *result = [self findOrCreateDirectory:NSApplicationSupportDirectory
                                          inDomain:NSUserDomainMask
                               appendPathComponent:dirName
                                             error:&error];
    
    if (!result) {
        DDLogError(@"Unable to find or create application support directory:\n%@", error);
    }
    
    return result;
}

@end