No it will not hamper your performance. If you face issue with loading large or many files, see this-Is it possible to load a compressed audio file directly into a buffer, without conversion?
Get all folder and subfolder.
For Obj c:
NSArray *mainpaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDir = [mainpaths objectAtIndex:0];
NSFileManager *Filemanager = [NSFileManager defaultManager];
NSArray *fileList = [Filemanager contentsOfDirectoryAtPath:documentsDir error:nil];
for (NSString *s in fileList){
NSLog(@"YOu subfolder--%@", s);
}
For swift:
let documentsDirectory = try! NSFileManager().URLForDirectory(.DocumentDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: true)
let fileEnumerator = NSFileManager.defaultManager().enumeratorAtURL(documentsDirectory, includingPropertiesForKeys: nil, options: NSDirectoryEnumerationOptions(), errorHandler: nil)
while let file = fileEnumerator?.nextObject() {
//get all file name here.
}