Multithreading in Swift

The best resource to learn about multithreading in Swift is https://theswiftdev.com/ultimate-grand-central-dispatch-tutorial-in-swift/

Swift enum - make Encodable

Suppose you have struct like below to encode as { status: "",  macName: "" }

struct Request: Encodable {

      var status: MacStatus
      var macName: String
}

enum MacStatus {

    case running
    case notRunning
}

Now we want to make the enum  MacStatus as encodable. So we can use singleValueContainer

extension MacStatus: Encodable {

    var josnKey: String {
        switch self {
        case . running:
            return "Running"
        case . notRunning:
            return "Not Running"
   }

    public func encode(to encoder: Encoder) throws {
        var container = encoder.singleValueContainer()
        try container.encode(josnKey)
    }
}

Another way is below:

enum MacStatus: String, Encodable {

    case running
    case notRunning

   var rawValue {
       switch self {
           case . running:
                return "Running"
           case . notRunning:
                return "Not Running"
       }
   }
}

Xcode error : not valid for use in process using Library Validation: mapping process and mapped file (non-platform) have different Team IDs

1. Xcode -> Product -> Clean Build Folder

2. Xcode -> Preferences -> Locations -> Go to Dervied Data and delete the folders named with your project name

Swift Code Review

When we work on a project as team, we want to make sure all of team members follow some rules

- to keep good coding practice
- to maintain the code looks similar
- to reduce bugs
- to improve performance

One of the best way to follow good swift styles is using Swift Lint

Here are some other tips for code review:

1.
Reduce the use of red text. We have to keep an eye on the text with red colour ( I am mentioning the Xcode default format).
The only text in red colour should be the key in Localizable.strings file or some print statements.

2.
Reduce the usage of 'self.'
The only place 'self.'  can exist should the init() or constructors of a class.
If we forced to use self in any closures, then apply [weak self] for the arguments and add a guard statement. Check below example:

CameraController.requestCameraAccess(completion: { [weak self] (status) in

  guard let strongSelf = self else { return }

  if status {

    globalMainQueue.async {

      strongSelf.performRoomSelection(model: model, cellIndex: cellIndex)

    }

  }

})

3. Reduce the usage of integer or string constants.

group it using enum if possible.

4. Inherit NSObject only if necessary.

5. Check all delegate vars are declared as 'weak'

iOS - Fix Massive View Controller using MVP+VM Architecture

To solve the Massive View Controller, we distribute the tasks to different classes:

1. Router

• The Router class will capable to handle all navigations such as segue or custom.
• Capable to construct the view controller
• Capable to pass data to other view controllers

A sample Router class is shown below:


So we will always call addContracts() function when ever construct a view controller

func showLoginByRemove(_ viewController: UIViewController?) {

        let loginController = LoginViewController.getController()

        LoginRouter.addContracts(loginController, parent: self, profile: MyProfile())

        transition(fromVC: viewController, animationDuration: 0.5, toVC: loginController)

}

2. SBControl
    This class will keep all storyboard controls, and its makeups such as setting font, colours and localised texts and animations etc..

I am not repeating how to do this, Its well explained here see the section "Solution 2: Presentation Controls"

So
The VC (View Controller) can have minimum one IBOutlet reference to the Object control.

3. Presenter  - implements UIEvents protocol
    Responsible to handle user actions from View Controller. This is just a dispatcher. Handle a little business logics. Presenter will ask to viewmodel to perform the data manipulations and will return the result to the view controller using the DisplayUI protocol which is implemented by View Controller.
    Presenter will give the navigation task to the router
    Presenter will give the display task to the view controller
    Presenter will give the network operations to the service class

4. Service - optional
     Responsible to all network operations. Presenter will hold a protocol reference which is implemented by Service class

5. ViewModel
     There will be separate view models for each view. It will be responsible to handle business logic as well as the presentation logic. Both will be grouped using protocols.

6. ViewController
    Responsible to the VC life cycle. Inform all UI actions to the Presenter. ViewController implements a DisplayUI protocol.

7. UIController (optional)
    Handle the tableview/collection/text view delegates here to reduce the code in View Controller and also to distribute the functionalities.




Following is the template to create the files.

https://github.com/davidpaul0880/Swift-Template

Can post more when get more free time..

But post comment if you have any questions, or need clarifications.

OpenOffice. - Freeze or Scroll Lock the first row or any row or column.

If you want to freeze first row, then select the second row and in menu. Window -> Freeze.

Convert Localizable.strings to a spread sheet or csv / xls file

"label.welcome" = "Welcome";//welcome message in splash screen


1. Rename the Localizable.strings file to Localizable.csv and open it in OpenOffice.

2. Give the separator as “=“ and //

Then we can save as it in our format such as .xls

Some iOS Interview Questions

1. What are the application states

2. UIViewController Life Cycle in the order. 

3. Whats the minimum number of constraints we need for a UIView

4. Whats the minimum number of constraints we need for a UIButton/UILabel/UIImageView

5. Can we create an app without using a UIViewController
6. spa size swift vs objc
7. performance swift vs objc
8. xml vs json
9. Swift server side
10. Tableview Prefetch protocol
11. GCD vs OperationQ
12. AssociatedType, Generic
13. Coredata - multithreading
14. Design patterns
15. MVVM
16. enum objc vs swift
17. Closure
18. weak vs unowned
19. open vs public

Error - You have selected the Production server, yet your Certificate does not appear to be the Production certificate! Please check to ensure you have the correct certificate!

This is the error got from our .NET team when trying to push messages to iOS device with AdHoc/AppStore profile.

The issue was with the certificate file (.p12). 

When we create certificate (.p12) , Always export like selecting the certificate only. see the attached image

Swift - Crash 'Bad Access' with Release mode Xcode 7.1.1

sortInPlace function of array is crashing when running on iOS8 6+ device. 

Its fixed with Xcode 7.2 version

Best way to install plugins for Xcode is Alcatraz

Go here for more details

Malayalam Keyboard for iPhone and iPad

 

With Varamozhi, you can type in Manglish and you will see text in real Malayalam.

Varamozhi is now a custom Keyboard. Follow instructions in Setup & Usage to enable Keyboard.

https://itunes.apple.com/in/app/varamozhi/id514987251?mt=8

Convert svg file to png file on Mac

To Convert an vector (.svg) file into a png file , we can use command line

Open Terminal application.

switch to the directory (use cd comand) where the svg file contain

qlmanage -t -s 1024 -o . myvectorfile.svg

This will create a png file named myvectorfile.svg.png with 1024*1024 dimension in the same folder.

* tested on Mac OS X 10.10.1

To filter Wireshark results for a specific IP

ip.dst == xx.xx.xxx.xxx || ip.src == xx.xx.xxx.xxx

The app X was not installed on the iPad because the app could not be found.

We may get this error message when install application on iPad

here is a helpful link

http://www.imore.com/daily-tip-fix-app-apps-itunes

Or try to delete from the library and re-download them from the app store, then try again.

Type malayalam on Mac machine

We can use the Keymagic application for OS X. Go to http://faisal.in/type-malayalam/ to download and install.

We can get the malayalam font RachanaMac from here

നന്ദി. :)

Another helpful link for malayalam typing/reading  is www.33dots.com/index.php/web/to-read-and-type-malayalam.html

Xcode 4.6.2 - PCH file built from a different branch

After updating Xcode 4.6.2, got error like

error: PCH file built from a different branch ((clang-425.0.27)) than the compiler ((clang-425.0.28)) xcode 4.6.2

After do a Clean (Product -> Clean) its disappeared :)

iOS - Search or compare korean text

In our UItableView search, we are using the below code to search a typed text in the cell content

 NSComparisonResult result = [eachCellContent compare:searchText options:NSDiacriticInsensitiveSearch|NSCaseInsensitiveSearch range:NSMakeRange(0, [searchText length])];

This is working fine. But this is not working with korean text.

E.g:
suppose one of the cell text is "소".//we are getting this combination by typing these two letters   ㅅ and ㅗ
If we type ㅅ only , our compare method is not working and so not listing the "소". (it is working if we type both ㅅ and ㅗ )

But the above example is working well with AddressBook application.

Is there any other compare method to support this ? (we also need this NSDiacriticInsensitiveSearch|NSCaseInsensitiveSearch )

Updated on 2013-01-14

Got solution from stackoverflow

NSString *normalizedContent = [eachCellContent decomposedStringWithCanonicalMapping];
NSString *normalizedSearch = [searchText decomposedStringWithCanonicalMapping];

and then compare these.

---

NSString *eachCellContent = @"소";
NSString *searchText = @"ㅅ";

NSString *normalizedContent = [eachCellContent decomposedStringWithCanonicalMapping];
NSString *normalizedSearch = [searchText decomposedStringWithCanonicalMapping];

NSComparisonResult result = [normalizedContent compare:normalizedSearch
                                               options:NSDiacriticInsensitiveSearch|NSCaseInsensitiveSearch
                                                 range:NSMakeRange(0, [normalizedSearch length])
                                                locale:[NSLocale currentLocale]];
if (result == NSOrderedSame) {
    NSLog(@"same");
}
// Output: same