Creating a pop up button interface

问题:

In Apple's stock 'Messages' app, tapping the camera button reveals popup buttons allowing the user to take a photo/video or choose an existing one. How would I implemented this same button design? Is the procedure the same for both iPhone & iPad?

回答1:

It's called a UIActionSheet. You use it like this

UIActionSheet *action = [[UIActionSheet alloc] initWithTitle:@"Foo" delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil otherButtonTitles:@"foo1", @"foo2", nil];
[action showInView:self.view];

(change the foos to whatever). To detect what button was clicked, implement the UIActionSheetDelegate's actionSheet:clickedButtonAtIndex: delegate method. For example:

- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex{
    NSString *title = [actionSheet buttonTitleAtIndex:buttonIndex];
    if ([title isEqualToString:@"foo1"]) {
        // do stuff...
    }
}

And yes, this works on both the iPhone and iPad (as @bobnoble pointed out, the iPad version uses a popover view, not an action sheet, but action sheets work on both).