Change signature

The Change Signature refactoring combines several different modifications that can be applied to a method/function signature. You can use this refactoring to:

change the method/function name and return type
add, remove, and reorder parameters
change parameter names and types
change the visibility type (for Swift) and the callable type (for Objective-C)

When changing a method/function signature, AppCode searches for all usages of the method/function and updates all the calls, implementations, and override replacements of the method/function that can be safely modified to reflect the change.

Changing a method/function signature

Position the caret at the name of the method/function that you want to refactor.
Press ⌃ F6. Alternatively, select Refactor | Change Signature from the main or context menu. The Change Signature dialog opens.
In the Change Signature dialog, make necessary changes to the method/function signature depending on your needs:
- For Objective-C: change the type of a callable procedure. In the Callable Type filed, select Function, Method, or Block.
- For Swift: change the visibility type. In the Visibility field, select public, internal, private, or another type.
- Change the method/function name. To change the name, edit the text in the Name field.
- Change the method/function return type by editing the contents of the Return type field.
- Manage the method/function parameters. To configure the parameters, use the table and buttons in the Parameters area:
  - To add a new parameter, click and specify the new parameter's properties in the corresponding table row.
    Auto-completion is available when typing the parameter type.
  - To remove a parameter, select any row and click .
  - To reorder the parameters, click and .
To see the expected changes and make adjustments prior to the refactoring, click Preview (available for Objective-C only) .
Click Refactor.

Examples

Swift: Change the method signature

Let's refactor the following method:

    func addTextForCell(item: MyListItem, cell: UITableViewCell) {
        let label = cell.viewWithTag(1000) as! UILabel
        label.text = item.text
    }
             

This method displays the text stored in the text property of the MyListItem class in a table view cell (UITableViewCell). With the Change Signature refactoring, you can make the method declaration more descriptive.

Place the caret at the method's name and press ⌃ F6. The Change Signature dialog opens:
In the Name field, type the new name: setUpText.
Swap the parameters by clicking or :
Rename the parameters and add internal names for them to make the method declaration more fluent and precise: change cell and item to for cell and with item. To do this, select the parameter in the table and type the new values in the fields that appear:
In the Signature Preview field, you can see how the new method signature will look:
Click Refactor to apply the changes. The method signature will be changed in the method declaration and all its usages:
func setUpText(for cell: UITableViewCell, with item: ChecklistItem) { let label = cell.viewWithTag(1000) as! UILabel label.text = item.text }

Objective-C: Convert a function into a block

Place the caret at the isPasswordValid function and press ⌃ F6.
In the dialog that opens, select Block in the Callable Type list.
Click Refactor.

Before	After
// This function will be converted into a block BOOL isPasswordValid(NSString *password) { return password.length > 4; } - (void)performLogin { // ... // Function's call if (isPasswordValid(password) == NO) { // ... } }	- (void)performLogin { // ... // New block if (^BOOL(NSString *password) { return password.length > 4; }(password) == NO) // ... }

Last modified: 27 August 2021