Instance Method

resourceValuesForKeys:error:

Returns the resource values for the properties identified by specified array of keys.

Declaration

- (NSDictionary<NSURLResourceKey, id> *)resourceValuesForKeys:(NSArray<NSURLResourceKey> *)keys error:(NSError * _Nullable *)error;

Parameters

keys

An array of property keys for the desired resource properties.

error

The error that occurred if one or more resource values could not be retrieved. This parameter is optional. If you are not interested in receiving error information, you can pass nil.

Return Value

A dictionary of resource values indexed by key.

Discussion

This method first checks if the URL object already caches the specified resource values. If so, it returns the cached resource values to the caller. If not, then this method synchronously obtains the resource values from the backing store, adds the resource values to the URL object's cache, and returns the resource values to the caller.

The type of the returned resource value varies by resource property; for details, see the documentation for the key you want to access.

If the result dictionary does not contain a resource value for one or more of the requested resource keys, it means those resource properties are not available for the URL, and no errors occurred when determining those resource properties were not available.

If an error occurs, this method returns nil and populates the object pointer referenced by error with additional information.

See Also

Accessing Resource Values

- getResourceValue:forKey:error:

Returns the value of the resource property for the specified key.

- setResourceValue:forKey:error:

Sets the URL’s resource property for a given key to a given value.

- setResourceValues:error:

Sets the URL’s resource properties for a given set of keys to a given set of values.

- removeAllCachedResourceValues

Removes all cached resource values and temporary resource values from the URL object.

- removeCachedResourceValueForKey:

Removes the cached resource value identified by a given key from the URL object.

- setTemporaryResourceValue:forKey:

Sets a temporary resource value on the URL object.

NSURLResourceKey

Keys that apply to file system URLs.