epic refactorings - melbourne cocoaheads june 2011

epic refactorings andpatterns to makeyour code awesome

jesse collis (@sirjec)luke cunningham (@icaruswings)

firstly, read this book!

we did and itmade us betterengineers

insert a pic of usreading our bookshaving a‘lightbulb’ moment

we do agile...

write the minimumamount of code toimplement the story

12 months later...

1 small card

But that isn’twhat this talk isabout

just too much for oneview controller

the problem

First Diagram

alright stop!refactor time.

first problem

view controllers needonly worry aboutstandard UIViews andmanage the display.

coordination andcontainment!

ViewCoordinatorview lifecycle

@protocol ViewCoordinator <NSObject>

- (UIView *)view;

- (void)viewWillAppear;

- (void)viewDidAppear;

- (void)viewWillDisappear;

- (void)viewDidDisappear;

- (void)viewDidUnload;

- (void)didReceiveMemoryWarning;

@end

@interface YourViewController : UIViewController {

id<ViewCoordinator> viewCoordinator_;

}

...

@end

@implementation YourViewController

- (id)initWithNibName... { viewCoordinator_ = [[MyViewCoordinator alloc] init];}

- (void)loadView { [super loadView]; [self.view addSubview:[viewCoordinator_ view]];}

- (void)viewWillAppear { [[viewCoordinator_ view] viewWillAppear];}

...

@end

single responsibility

a class should onlyhave one reason tochange.

second problem

they’re notsimple views

ListCoordinatorbasic selectioncallbacks

@protocol ListCoordinator

- (void)onSelectListItem:^(id)block;

...

@end

@interface YourViewController : UIViewController {

id<ViewCoordinator> viewCoordinator_;

id<ViewCoordinator, ListViewCoordinator> listCoordinator_;

}

...

@end

@implementation YourViewController

- (id)initWithNibName... { listCoordinator_ = [[MyListCoordinator alloc] init];

[listCoordinator_ onSelectListItem:^(id listing) { [self showListing:listing]; }];}

- (void)showListing:(Listing *)listing;{

...

}

...

@end

interface segregation

clients should notbe forced to dependon methods theydon’t use.

QueryCoordinatorafter configure/cancel configurecallbacks

SearchBarCoord...

and so on...

now ourstructure is morelike this...

Go to Xcode

under the hood

EventDispatcher

@interface MapCooordinator <ViewCoordinator, ListCoordinator>{ ...}

@end

@implementation MapCoordinator

...

- (void)onSelectListItem:^(Listing *)block;{ [eventDispatcher_ on:@"select-listing” performWithObject:block];}

- (void)mapView:(... *)mapView didSelectAnnotationView:(... *)view;{ Listing *listing = ... find listing ... [eventDispatcher_ fire:@"select-listing" withObject:listing];}

...

@end

there are nospecial cases

If you implementpatterns - follow your patterns

Coming in iOS5

thanks,jesse collis (@sirjec)luke cunningham (@icaruswings)