1.  Codable = Decodable + Encodable

What is Codable? Codable is to convert the JSON data object to an actual Swift class or struct and vice versa.

It’s usually used when the case you wanna retrieve or parse JSON data from the server like the APIs.

source: https://medium.com/doyeona/codable-decodable-encodable-feat-json-5643dc3d7766

2.  In Xcode Version 12.5  warning when creating a class in protocol

Xcode 12 when I create protocol "class" it be a warning, you should be changed to "AnyObject"

3.  Amount Round down swift

let amountRoundDownOneHundred = 123456

print((amountRoundDownOneHundred/100) * 100)  // 123400

4.  Error use windows UIScreen

Error when use  -> self.window = UIWindow(frame: UIScreen.main.bounds)

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Application windows are expected to have a root view controller at the end of application launch'
terminating with uncaught exception of type NSException
CoreSimulator 757.5 - Device: iPhone 12 (0000-0B56-000-B641-0000) - Runtime: iOS 14.5 (18E182) - DeviceType: iPhone 12

Solution if simulator or device run in ios 13, *  delete  self.window = UIWindow(frame: UIScreen.main.bounds) . if you don't have sceneDelegate

5.  Blink Black screen after lunchscreen 

Solution:
Call topOverlay function in  didFinishLaunchingWithOptions Appdelegate:

   private func topOverlay() {
        self.window?.windowLevel = UIWindow.Level(rawValue: CGFloat.greatestFiniteMagnitude)
        self.window?.backgroundColor = .darkSkyBlue
        self.window?.frame = UIScreen.main.bounds
        self.window?.rootViewController = UIViewController()
        self.window?.alpha = 1.0
        self.window?.isHidden = false
        self.window?.makeKeyAndVisible()
    }

6.  Convert Date time format

Convert date time with string data   2021-05-20 13:47:31  to this string data Thursday, May 20, 2021 - 13:47. so follow this code below.

private func dateConvert(strDate: String) -> String {
        let dateFormatterGet = DateFormatter()
        dateFormatterGet.dateFormat = "yyyy-MM-dd HH:mm:ss"
        
        let dateFormatterPrint = DateFormatter()
        dateFormatterPrint.dateFormat = "EEEE, MMM d, yyyy - HH:mm"
        
        if let date = dateFormatterGet.date(from: strDate) {
            return dateFormatterPrint.string(from: date)
        } else {
            return strDate
        }
    }    

result:

let dateFrom = "2021-05-20 13:47:31"
prtint(dateConvert(strdate: dateFrom)) 
// Thursday, May 20, 2021 - 13:47

7. Rotate UIImageView or UIView

use this extension

 /**
     Rotate a view by specified degrees
     
     - parameter angle: angle in degrees
     */
    func rotate(angle: CGFloat) {
        let radians = angle / 180.0 * CGFloat.pi
        let rotation = self.transform.rotated(by: radians)
        self.transform = rotation
    }

8. Fastlane command not found in terminal

zsh: command not found: fastlane

in terminal:

$ sudo gem install fastlane -NV

source: https://stackoverflow.com/a/43088169/8366535

9. Error pod install in Big Sur

When running in OS BigSur and you run pod install in terminal get this error

Your Podfile requires that the plugin `cocoapods-binary` be installed.

this one of solutions I've found

$sudo arch -x86_64 gem install ffi
$arch -x86_64 pod install