sartak / IIDelegate

create inline delegates for specific protocols like UITableViewDataSource on the fly

Leave it to IIDelegate

[IIDelegate delegateForProtocol:@protocol(...) withMethods:@{...}] creates a new class, at runtime, that conforms to the given protocol and responds to the specified methods. It then returns an instance of that new class so you can plug it into a UIKit delegate or elsewhere. IIDelegate converts a protocol-based API into a block-based API.

New in version two is a piece-wise delegate production API. You create a new class with [IIDelegate delegateClassForProtocol:@protocol(...)] and then you can call [class addSelector:@selector(...) withImplementation:^{...}] as many times as you wish. Call [class finalizeDelegate] to receive your instance (and to give the system a chance to close the class up).

This means you can use Objective C's closure capabilities to bind data directly to your actions, rather than needing to fake it by adding hacky attributes on your view controller. IIDelegate also saves you from having to litter your delegate code throughout many different methods. If you have ever dealt with multiple instances of UIAlertView, UIActionSheet, or UITableView in one view controller, your bones rattle with these pains.

You can use the closure nature of blocks to capture your necessary state. This can of course include capturing self with access its properties and methods. So there's no need to declare ivars.

You'll also need to set -fno-objc-arc on IIDelegate.m because objc_disposeClassPair is incompatible with ARC. Boo! (patches very much welcome)

Create a UITableViewDataSource delegate on the fly:

-(id) dataSourceForArray:(NSArray *)array {
    return [IIDelegate delegateForProtocol:@protocol(UITableViewDataSource)
                               withMethods:@{
        @"tableView:numberOfRowsInSection:":^NSInteger(id _delegate, UITableView *tableView, NSInteger section) {
            return [array count];
        },
        @"tableView:cellForRowAtIndexPath:":^UITableViewCell*(id _delegate, UITableView *tableView, NSIndexPath *indexPath) {
            UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];
            NSString *name = array[indexPath.row];
            cell.textLabel.text = name;
            return cell;
        },
    }];
}

-(void) viewDidLoad {
    NSArray *states = @[@"AL", @"AK", @"AZ", @"AR", @"CA", @"CO", @"CT", @"DE", @"FL", @"GA", @"HI", @"ID", @"IL", @"IN", @"IA", @"KS", @"KY", @"ME", @"MD", @"MA", @"MI", @"MN", @"MS", @"MO", @"MT", @"NE", @"NV", @"NH", @"NJ", @"NM", @"NY", @"NC", @"ND", @"OH", @"OK", @"OR", @"PA", @"RI", @"SC", @"SD", @"TN", @"TX", @"VT", @"VI", @"VA", @"WA", @"WV", @"WI"];
    NSArray *prefectures = @[@"北海道", @"青森", @"岩手", @"宮城", @"秋田", @"山形", @"福島", @"茨城", @"栃木", @"群馬", @"埼玉", @"千葉", @"東京", @"神奈川", @"新潟", @"富山", @"石川", @"福井", @"山梨", @"長野", @"岐阜", @"静岡", @"愛知", @"三重", @"滋賀", @"京都", @"大阪", @"兵庫", @"奈良", @"和歌山", @"鳥取", @"島根", @"岡山", @"広島", @"山口", @"徳島", @"香川", @"愛媛", @"高知", @"福岡", @"佐賀", @"長崎", @"熊本", @"大分", @"宮崎", @"鹿児島", @"沖縄"];

    self.stateTable.dataSource = [self dataSourceForArray:states];
    self.prefectureTable.dataSource = [self dataSourceForArray:prefectures];
}

Version 2 API:

-(id) dataSourceForArray:(NSArray *)array {
    Class class = [IIDelegate delegateClassForProtocol:@protocol(UITableViewDataSource)];

    [class addSelector:@selector(tableView:numberOfRowsInSection:)
           withImplementation:^NSInteger(id _delegate, UITableView *tableView, NSInteger section) {
               return [array count];
    }];

    [class addSelector:@selector(tableView:cellForRowAtIndexPath:)
           withImplementation:^UITableViewCell*(id _delegate, UITableView *tableView, NSIndexPath *indexPath) {
               UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];
               NSString *name = array[indexPath.row];
               cell.textLabel.text = name;
               return cell;
    }];

    return [class finalizeDelegate];
}

-(void) viewDidLoad {
    NSArray *states = @[@"AL", @"AK", @"AZ", @"AR", @"CA", @"CO", @"CT", @"DE", @"FL", @"GA", @"HI", @"ID", @"IL", @"IN", @"IA", @"KS", @"KY", @"ME", @"MD", @"MA", @"MI", @"MN", @"MS", @"MO", @"MT", @"NE", @"NV", @"NH", @"NJ", @"NM", @"NY", @"NC", @"ND", @"OH", @"OK", @"OR", @"PA", @"RI", @"SC", @"SD", @"TN", @"TX", @"VT", @"VI", @"VA", @"WA", @"WV", @"WI"];
    NSArray *prefectures = @[@"北海道", @"青森", @"岩手", @"宮城", @"秋田", @"山形", @"福島", @"茨城", @"栃木", @"群馬", @"埼玉", @"千葉", @"東京", @"神奈川", @"新潟", @"富山", @"石川", @"福井", @"山梨", @"長野", @"岐阜", @"静岡", @"愛知", @"三重", @"滋賀", @"京都", @"大阪", @"兵庫", @"奈良", @"和歌山", @"鳥取", @"島根", @"岡山", @"広島", @"山口", @"徳島", @"香川", @"愛媛", @"高知", @"福岡", @"佐賀", @"長崎", @"熊本", @"大分", @"宮崎", @"鹿児島", @"沖縄"];

    self.stateTable.dataSource = [self dataSourceForArray:states];
    self.prefectureTable.dataSource = [self dataSourceForArray:prefectures];
}

Create a UIActionSheetDelegate on the fly:

-(IBAction) tappedDelete:(Record *)record {
    id delegate = [IIDelegate delegateForProtocol:@protocol(UIActionSheetDelegate)
                                      withMethods:@{
        @"actionSheet:willDismissWithButtonIndex:":^(id _delegate, UIActionSheet *actionSheet, NSInteger buttonIndex) {
            if (buttonIndex == actionSheet.destructiveButtonIndex) {
                [record delete];
            }
            else if (buttonIndex == actionSheet.firstOtherButtonIndex) {
                [record setImmortal];
            }
        },
    }];

    UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"You Serious?"
                                                             delegate:delegate
                                                    cancelButtonTitle:@"Cancel"
                                               destructiveButtonTitle:@"Delete"
                                                    otherButtonTitles:@"Never", nil];
    [actionSheet showInView:self.view];
}