Code Quality Management (iOS)

Arpit Kulshrestha

Prefix for Files and Folders in iOS ProjectsUse two letter in Capital Prefix for every file and Folder of your project

If Application Name contain two words use first letter of each

If Application Name contain one word use first two letters.

Don’t use Prefix for library code , code from outside, General manager use commonly in Every iOS Project

Example : SnapDeal => SDBaseViewController, Sware => SWBaseView

Code OrganizationUse these two commenting style 1. / / / (inline) 2. /** */ (block)

Use “// MARK: <Specific purpose of Methods>” for set of function in Swift File

Documentation Style :- 1. Description 2. Parameters 3. Throws 4.Returns

Global Constants HandlingUse one dedicated file for managing constants which is used globally

That file name should clearly indicate the purpose like - GlobalConfiguration, AppConfiguration, GlobalConstants, ProjectHeader etc.

Use “static let” , Nerver use “public let” or “let”

Use Struct to categorize specific type of constants for clear visibility

Use nested Struct to better manage constants

For constants naming use lowerCamelCase

Class Constant - type propertyIf too many different type of constants then use Struct to categorize

like tableCellName, errorMessages etc

If not too much constants use direct “static let” without struct inside class

DON’T use Nested struct in Class Swift File

Name of struct should define its purpose

Class And Struct - When & How to useStruct and Enumerations are value type and class is reference type

Use struct for holding set of values such as array, date, string and pass around the program in iOS Project

Use struct for data calculations, conversions, manipulations etc as well

Best use for Utils / Helper / Common code

Don’t use for Data Models

Since structs can not be subclassed so you must implement “static” functions in it.

Class - Type MethodsWhen required to subclass or inherit use “class” such as

viewcontrollers, custom controls, data models etc.

Type Methods - (Methods access without instance / via class name)

Use “class func” (if you want to override in future via subclassing) OR “static func” (if you just want to use from same class not for overriding )

Use type methods for reusability of codes Or for specific purpose classes which required less , minimal processing.

Class - Singleton PatternUse Singleton Pattern for major processing / crucial tasks (Such as

Networking, DB, Writing / reading on disk, heavy downloading etc.)

Singleton Class should be of Specific purpose with defined tasks.

Don’t use Singleton for utility classes , general purpose handling, simple data storage for runtime.

Use “Static” instance Don’t do dispatch_once in Swift (you can do in Obj C) for getting single instance of Singleton.

Best Approach

Ok to use

Class - Factory Pattern

Every time you request you got new instance of class via initialization , comes in the segment of Factory Pattern.

Data Model Classes, ViewController Classes, base Classes, Custom classes comes in this.

Init - Designated and Convenience initConvenience initializers are secondary, supporting initializers for a

class.

You can define a convenience initializer to call a designated initializer from the same class as the convenience initializer with some of the designated initializer parameters set to default values.

You can also define a convenience initializer to create an instance of that class for a specific use case or input value type.

you cannot chain two designated initializer from the same class.

DeinitUse it for every clean up process in controller.

Only available for class type.

If there is no specific space for removing Notification observer and invalidating NStimer, do it in “deinit”.

If want to save something / data before deallocating that controller.

Category / ExtensionTo add Some extra feature for every component / UIControl of

Application then use Extensions.

Naming Conventions “String+Addition” , “Array+ <Feature Name>” of file

Protocols should be Implemented through extensions.

Util conversion / calculations methods which took parameters as basic types (String, NSDate, Array, Dictionary etc.) must be use with Extension not as Util Function.

UIViewControllers implementing ProtocolsPreferred:

class MyViewcontroller: BaseViewController { // class stuff here}

// MARK: - UITableViewDataSourceextension MyViewcontroller: UITableViewDataSource { // table view data source methods}

// MARK: - UIScrollViewDelegateextension MyViewcontroller: UIScrollViewDelegate { // scroll view delegate methods}

Not Preferred:

class MyViewcontroller: BaseViewController, UITableViewDataSource, UIScrollViewDelegate { // all methods}

SubclassingWhen you required some features for specific set of components &

controls.

Design for Custom View, Custom UI Controls.

For theming of Application Subclassing UItextField, UITextview, UILabel so any change from one class will impact on whole application.

If you want same function access than make base classes.

Such as SPBaseViewController, SPBaseNavigationController, SPBaseTabBarController etc.

Error HandlingWhen doing type conversion, file writing, reading, DB access,

Encoding, Decoding, Encryption, Security access, Hardware communication, location trace , in short those task have more chances of failure abruptly.

Use guard let statements to check for failure case so in else it can throw error of Custom type or Errortype.

Do - try - Catch

typealiasThe syntax for type aliasing a closure is unquestionably simpler than

the equivalent typedef in Objective-C

A type alias declaration introduces a named alias of an existing type into your program. Type alias declarations are declared using the keyword typealias and have the following form: typealias name = existing type

Handling Memory WarningsImplement Super Or Print in “didReceiveMemoryWarning” of

ViewController delegate method.

It started giving warning at 70 % percent memory use and crash on 100%

Also at App level “applicationDidReceiveMemoryWarning”

Make common methods which removes cache , images in memory etc whenever receive such warnings in application.

NSUserDefaults UseSeparate out its use via making getter setter commonly on

application level.

Only use when required to save single values/strings into permanent storage.

Not for Object , Json, long texts etc.

Don’t use Synchronize(), Not required after iOS 8. Use of Synchronize increase too much overhead and not good for performance.

Don’t remove keys in loop use “removePersistentDomainForName”

Image Assets UseDevices - Change ImageSet to Specific “iPhone” , “iPad”.

Don’t keep it Universal

For naming use lowercase, No Space , No special char

But use dash (-) not underscore (_)

Use all image set 1x , 2x , 3x for sure

If Application size increases too much you have flexibility to delete 1x images.

Data Model ClassesPrefer to use ObjectMapper for Parsing and filling models from JSON or

XML.

init() should be there for every Model Class.

If not using ObjectMapper, there must be initWithDict(), dictRepresentation() methods in Model class.

For Communication between viewcontrollers, model objects should be use throughout the project.

UIApplicationSingle Instance of App, handle remote notification, schedule local

notification, app state handling, background task execution.

If your app must handle incoming events before the system does—”a very rare situation”—you can implement a custom event or action dispatching mechanism.

To do this, subclass UIApplication and override the sendEvent(_:) and /or the sendAction(_:to:from:for:) methods.

User credential storageNever use NSUserDefaults / Sqlite / Core Data / DB / Plist to save user

credential information.

You have to encrypted the file somehow.

Best to use Keychain Storage with the help of Apple keychainWrapper class.

The Keychain, uses the Triple Digital Encryption Standard (3DES) to encrypt its data.

MultithreadingGCD for little tasks which is not dependent on other tasks.

Use Operation / NSOperation , queue concept for big dependent multiple tasks.

Always Subclass Operation , and make your own operation making its object and add it into Operation Queue.

Library & toolsDon’t use any library until & unless Programming Community not

talking about it.

First Compare on https://www.libhunt.com/

Try to solve problems with custom codes, subclassing existing classes not with external pod library.

Keep on Exception breakpoint during debugging.

Run Static Analyzer in every few days to find out leaks.

If Not able to find reason of crash via breakpoint , debugging, use Instrument - Zombies.

Use FileMerge, Prepo, JSONExport, Postmain etc to save time.

User Interface - Best PracticesUse UITableView and UICollectionView for increasing, regular changing

and dynamic data components.

Usually try to avoid UIScrollview for dynamic data components.

Create touch control around 44 x 44 so it should be easily hit target on touch.

If UI is changing too much on run time or when user actioned on device than prefer to make UI with programming.

Don’t left log for App DistributionImportant Credential , info, Request , Response shouldn’t be logged

specially in case of App Distribution / Release.

Use DLog, Or Just print in case of Debugging only.

General Programming TipsMethod braces and other braces (if/else/switch/while

etc.) It prefered to open on the same line as the statement but close on a new line.

You can re-indent by selecting some code (select all) and then Control-I (Editor\Structure\Re-Indent in the menu).

Whitespace within methods should separate functionality, but having too many sections in a method often means you should refactor into several methods.

Colons always have no space on the left and one space on the right. Exceptions are the ternary operator ? : and empty dictionary [ : ].

class TestDatabase: Database { var data: [String: CGFloat] = ["A": 1.2, "B": 3.2] }

For Empty arrays and Dictionary, use type annotations

Preferred:

var names: [String] = []var lookup: [String: Int] = [:]

Not Preferred:

var names = [String]()var lookup = [String: Int]()

Prefer shortcut versions of type Declarations rather than full generics

syntaxPreferred:

var deviceModels: [String]var employees: [Int: String]var faxNumber: Int?

Not Preferred:

var deviceModels: Array<String>var employees: Dictionary<Int, String>var faxNumber: Optional<Int>

Prefer the for-in style over while/repeat whilePreferred:

for _ in 0..<3 { print("Hello three times")}

for (index, person) in attendeeList.enumerate() { print("\(person) is at position #\(index)")}

for index in 0.stride(to: items.count, by: 2) { print(index)}

for index in (0...3).reverse() { print(index)}

When multiple optionals are unwrapped , minimize nesting

Preferred:

guard let number1 = number1, number2 = number2, number3 = number3 else { fatalError("impossible") }// do something with numbers

Not Preferred:

if let number1 = number1 { if let number2 = number2 { if let number3 = number3 { // do something with numbers } else { fatalError("impossible") } ….. So on

iOS Architecture And Code FlowTravel App

1.Module / Business Manager

- Journey Manager

- Ticket Manager

- Stay Manager

2. Task Manager

- DB Manager - Validation Manager

- Network Manager - Download Manager

Continue...3. Task Handler

- Error handler

- File Handler

4. Data Model Classes

5. View Controllers

6. Other

- Util - Helper - Resources - Image Assets

- GlobalConfiguration - Bridging Header

Code Flow

Continue….One Module/ Business Manager should only handle max 6-8

Controllers.

If Task Managers have lot of tasks which seems like it would be so big separate it into Task handlers.

Every Module must have a separate Storyboard file for UI.

If Util is going to be so big separate it into 2-3 Swift files will increase the readability like - AppUtil and InterfaceUtill / UIUtil

Protocol Oriented Programming (Swift 2 +)

Swift claiming to be first POP language.

This new methodology of coding will not entirely replace object-oriented programming, it does bring a number of very useful, new possibilities.

Protocol Extension - Make Protocol + Extend + implement in ViewController.

For Now , Don’t use for Production App, Just Practice.