Mobile Architecture

Chris Jimenez

Mobile Architecture

En el principio de los tiempos...

MVC

Cons

◦ Massive View Controller!◦ Sometimes hard to test◦ More “layers” are needed as app grows

◦ Its an “Apple thing”◦ Decrease code clarity◦ There are better design patterns

What better you say?

MVVM - Model View View Model--iOSMVP - Model View Presenter--Android

MVVM

◦ View controllers are technically distinct components, they almost always go hand-in-hand together, paired

◦ When is the last time that a view could be paired with different view controllers??

MVVM

So why not formalize their connection?

MVVM

◦ Most of the stuff in ViewController is presentation logic

◦ Things like transforming values from the model into something the view can present

MVVM

MVVM to the rescue

MVVM

MVVM is an augmented version of MVC where we formally connect the view and controller, and move presentation logic out of the controller and into a new object.

MVVM

Why?◦ Reduces the complexity of one’s view controllers and makes one’s presentation logic easier to test

Some Code

@interface Person : NSObject

- (instancetype)initwithSalutation:(NSString *)salutation firstName:(NSString

*)firstName lastName:(NSString *)lastName birthdate:(NSDate *)birthdate;

@property (nonatomic, readonly) NSString *salutation;

@property (nonatomic, readonly) NSString *firstName;

@property (nonatomic, readonly) NSString *lastName;

@property (nonatomic, readonly) NSDate *birthdate;

@end

PersonViewController.m

- (void)viewDidLoad {

[super viewDidLoad];

if (self.model.salutation.length > 0) {

self.nameLabel.text = [NSString stringWithFormat:@"%@ %@ %@", self.model.salutation,

self.model.firstName, self.model.lastName];

} else {

self.nameLabel.text = [NSString stringWithFormat:@"%@ %@", self.model.firstName,

self.model.lastName];

}

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];

[dateFormatter setDateFormat:@"EEEE MMMM d, yyyy"];

self.birthdateLabel.text = [dateFormatter stringFromDate:model.birthdate];

}

Now with MVVM, PersonViewModel.h

@interface PersonViewModel : NSObject

- (instancetype)initWithPerson:(Person *)person;

@property (nonatomic, readonly) Person *person;

@property (nonatomic, readonly) NSString *nameText;

@property (nonatomic, readonly) NSString *birthdateText;

@end

PersonViewModel.m

@implementation PersonViewModel

- (instancetype)initWithPerson:(Person *)person {

self = [super init];

if (!self) return nil;

_person = person;

if (person.salutation.length > 0) {

_nameText = [NSString stringWithFormat:@"%@ %@ %@", self.person.salutation,

self.person.firstName, self.person.lastName];

} else {

_nameText = [NSString stringWithFormat:@"%@ %@", self.person.firstName,

self.person.lastName];

}

An our view controller

- (void)viewDidLoad {

[super viewDidLoad];

self.nameLabel.text = self.viewModel.nameText;

self.birthdateLabel.text = self.viewModel.birthdateText;

}

MVVM

Chiva!

MVP Model View Presenter

Presenter is a layer that provides View with data from Model. Presenter also handles background tasks.

Why?

◦ Keep it stupid simple◦ Removes complexity◦ Easy to test

Normal View Model in Android

On top of that

◦ View can disappear and appear at random time

◦ Do not forget about saving/restoring of Views

◦ Attach a couple of background tasks to that temporary Views

Model View Presenter

MVP Pros

◦ Complex tasks are split into simpler tasks and are easier to solve.

◦ Smaller objects, less bugs, easier to debug.

◦ Testable.

MVP Background Tasks

Background Tasks

Code time