Get device storage using NSFileManager API. This code will print the results of each possible NSSearchPathDirectory.

DeviceStorage.m

#import <Foundation/Foundation.h>

void logStorageForLocation(NSSearchPathDirectory location) {
	    NSError *error;
	    NSArray * const paths = NSSearchPathForDirectoriesInDomains(location, NSUserDomainMask, YES);
	    
	    NSDictionary *attributes = [[NSFileManager defaultManager] attributesOfFileSystemForPath:[paths lastObject]
	                                                                                       error:&error];
	    uint64_t totalSpace = 0;
	    uint64_t totalFreeSpace = 0;
	    
	    NSNumber *fileSystemSizeInBytes = [attributes objectForKey: NSFileSystemSize];
	    NSNumber *freeFileSystemSizeInBytes = [attributes objectForKey:NSFileSystemFreeSize];

	    totalSpace = [fileSystemSizeInBytes unsignedLongLongValue];
	    totalFreeSpace = [freeFileSystemSizeInBytes unsignedLongLongValue];

	    NSLog(@"Location: %d - Total space %llu MB  / Free Space %llu MB", location, ((totalSpace/1024ll)/1024ll), ((totalFreeSpace/1024ll)/1024ll));
}

int main(int argc, char *argv[]) {
	@autoreleasepool {
		  logStorageForLocation(NSApplicationDirectory);
		  logStorageForLocation(NSDemoApplicationDirectory);
		  logStorageForLocation(NSDeveloperApplicationDirectory);
		  logStorageForLocation(NSAdminApplicationDirectory);
		  logStorageForLocation(NSLibraryDirectory);
		  logStorageForLocation(NSDeveloperDirectory);
		  logStorageForLocation(NSUserDirectory);
		  logStorageForLocation(NSDocumentationDirectory);
		  logStorageForLocation(NSDocumentDirectory);
		  logStorageForLocation(NSCoreServiceDirectory);
		  logStorageForLocation(NSAutosavedInformationDirectory);
		  logStorageForLocation(NSDesktopDirectory);
		  logStorageForLocation(NSCachesDirectory);
		  logStorageForLocation(NSApplicationSupportDirectory);
		  logStorageForLocation(NSDownloadsDirectory);
		  logStorageForLocation(NSInputMethodsDirectory);
		  logStorageForLocation(NSMoviesDirectory);
		  logStorageForLocation(NSMusicDirectory);
		  logStorageForLocation(NSPicturesDirectory);
		  logStorageForLocation(NSPrinterDescriptionDirectory);
		  logStorageForLocation(NSSharedPublicDirectory);
		  logStorageForLocation(NSPreferencePanesDirectory);
		  //    logStorageForLocation(NSApplicationScriptsDirectory);
		  logStorageForLocation(NSItemReplacementDirectory);
		  logStorageForLocation(NSAllApplicationsDirectory);
		  logStorageForLocation(NSAllLibrariesDirectory);

	}
}