NSURL

Create

From NSString:

NSString *urlString = @"https://www.stackoverflow.com";
NSURL *myUrl = [NSURL URLWithString: urlString]; 

You can also use the following methods:

- initWithString:
+ URLWithString:relativeToURL:
- initWithString:relativeToURL:
+ fileURLWithPath:isDirectory:
- initFileURLWithPath:isDirectory:
+ fileURLWithPath:
- initFileURLWithPath:
 Designated Initializer
+ fileURLWithPathComponents:
+ URLByResolvingAliasFileAtURL:options:error:
+ URLByResolvingBookmarkData:options:relativeToURL:bookmarkDataIsStale:error:
- initByResolvingBookmarkData:options:relativeToURL:bookmarkDataIsStale:error:
+ fileURLWithFileSystemRepresentation:isDirectory:relativeToURL:
- getFileSystemRepresentation:maxLength:
- initFileURLWithFileSystemRepresentation:isDirectory:relativeToURL:

Compare NSURL

NSString *urlString = @"https://www.stackoverflow.com";

NSURL *myUrl = [NSURL URLWithString: urlString]; 
NSURL *myUrl2 = [NSURL URLWithString: urlString]; 

if ([myUrl isEqual:myUrl2]) return YES;

Modifying and Converting a File URL with removing and appending path

1. URLByDeletingPathExtension:

If the receiver represents the root path, this property contains a copy of the original URL. If the URL has multiple path extensions, only the last one is removed.

2. URLByAppendingPathExtension:

Returns a new URL made by appending a path extension to the original URL.

Example:

   NSUInteger count = 0;
        NSString *filePath = nil;
        do {
            NSString *extension = ( NSString *)UTTypeCopyPreferredTagWithClass(( CFStringRef)AVFileTypeQuickTimeMovie, kUTTagClassFilenameExtension);
            NSString *fileNameNoExtension = [[asset.defaultRepresentation.url URLByDeletingPathExtension] lastPathComponent];//Delete is used
            NSString *fileName = [NSString stringWithFormat:@"%@-%@-%u",fileNameNoExtension , AVAssetExportPresetLowQuality, count];
            filePath = NSTemporaryDirectory();
            filePath = [filePath stringByAppendingPathComponent:fileName];//Appending is used
            filePath = [filePath stringByAppendingPathExtension:extension];
            count++;

        } while ([[NSFileManager defaultManager] fileExistsAtPath:filePath]);

        NSURL *outputURL = [NSURL fileURLWithPath:filePath];