# write(to:atomically:) Writes a property list representation of the contents of the dictionary to a given URL. ``` func write(to url: URL, atomically: Bool) -> Bool ``` ## Parameters `url` The URL to which to write the dictionary. `atomically` A flag that specifies whether the output should be written atomically. If `atomically` is , the dictionary is written to an auxiliary location, and then the auxiliary location is renamed to `url` . If `atomically` is , the dictionary is written directly to `url` . The option guarantees that `url` , if it exists at all, won’t be corrupted even if the system should crash during writing. `atomically` is ignored if `url` is of a type that cannot be written atomically. ## Return Value if the location is written successfully, otherwise . ## Discussion This method recursively validates that all the contained objects are property list objects (instances of `NSData`, `NSDate`, `NSNumber`, `NSString`, `NSArray`, or `NSDictionary`) before writing out the file, and returns if all the objects are not property list objects, since the resultant output would not be a valid property list. If the dictionary’s contents are all property list objects, the location written by this method can be used to initialize a new dictionary with the class method `NSDictionary/init(contentsOfURL:)-98pl3` or the instance method `NSDictionary/init(contentsOfURL:)-4pv16`. If you need greater control over the property list representation, use [`PropertyListSerialization`](/documentation/Foundation/PropertyListSerialization) instead. For more information about property lists, see [Property List Programming Guide](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/PropertyLists/Introduction/Introduction.html#//apple_ref/doc/uid/10000048i). --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)