woolsweater / actionsheetdelegate Goto Github PK

ActionSheetDelegate is a simple way to create a delegate for a UIActionSheet. When creating an instance, you specify a "handler" Block whose signature matches that of the UIActionSheetDelegate method actionSheet:clickedButtonAtIndex:. ActionSheetDelegate conforms to the UIActionSheetDelegate protocol and thus implements that method.

You then create a sheet, passing your instance of ActionSheetDelegate for the delegate argument. When the sheet sends actionSheet:clickedButtonAtIndex:, the delegate simply passes the arguments on to its handler Block.

The class also has a handy method that uses the Objective-C runtime associated objects feature to tie its lifetime to its sheet's. Tying the two together this way means that there is no need to keep a local (or ivar-level) reference to the delegate; its only owner is the sheet itself, and it will be destroyed when the sheet is.

A quick example of usage:

ActionSheetDelegate * delegate;
delegate = [ActionSheetDelegate delegateWithHandler:
    ^( UIActionSheet * sheet, NSInteger idx ){
        if( idx == [sheet destructiveButtonIndex] ){
            [controller removeSomeImage];
        }
        else if( idx == [sheet firstOtherButtonIndex] ){
            [controller presentImagePicker];
        }
        // Cancel button "falls through" to no action
}];

UIActionSheet * sheet;
sheet = [[UIActionSheet alloc] initWithTitle:@""
                                    delegate:delegate
                           cancelButtonTitle:@"Cancel"
                      destructiveButtonTitle:@"Remove Image"
                           otherButtonTitles:@"Choose New Image", nil];
// Tie delegate's lifespan to that of the sheet
[delegate associateSelfWithSheet:sheet];

[sheet showInView:[self view]];

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