Rework building action sheets

[wutschel]

Taken from review discussions in #1232.

Current implementation uses a generic and complex action sheet handler, which compares localized strings to determine the action to take. Alternative solution is to create a set of the actions:

UIAlertAction *action1 = [UIAlertAction ... handler:^{ [self do_this] }];
UIAlertAction *action2 = [UIAlertAction ... handler:^{ [self do_that] }];

In this case I would need to move the logic of what I am finally showing in the action sheet (currently a simple array of action strings which is majorly defined in AppDelegate) to the place where I am building the sheet. And ideally replacing the string in AppDelegate with enums. Something like this:

AppDelegate:

menu.sheetActions = @[
    action_play,
    action_queue,
];

ViewController:

UIAlertAction *action1 = [UIAlertAction ... handler:^{ [self play] }];
UIAlertAction *action2 = [UIAlertAction ... handler:^{ [self queue] }];

for (actionID in sheetActions) |
    switch (actionID) {
        case action_play:
            [alertCtrl addAction: action1];
            break;
        case action_queue:
            [alertCtrl addAction: action2];
            break;
       default:
           break;
    }
}

[kambala-decapitator]

please point to a couple of examples in the codebase

[wutschel]

Examples in the current codebase are the implementations of (void)actionSheetHandler:(NSString*) in DetailViewController, ShowInfoViewController and NowPlaying. In these methods the actions are processed by patterns like

if ([actiontitle isEqualToString:LOCALIZED_STR(@"Queue after current")]) {
    [self addQueueAfterCurrent:YES];
}
else if ([actiontitle isEqualToString:LOCALIZED_STR(@"Queue")]) {
    [self addQueueAfterCurrent:NO];
}
...

The actions themselves are added by looping through a list of action strings in sheetActions:

for (NSString *actionName in sheetActions) {
    NSString *actiontitle = actionName;
    UIAlertAction *action = [UIAlertAction actionWithTitle:actiontitle style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        [self actionSheetHandler:actiontitle];
    }];
    [alertCtrl addAction:action];
}

The array sheetActions is usually defined in AppDelegate as part of the whole menu/UI hierarchy configuration.