pofat

/// Call this at main()
/// return: time in milliseconds
func getPreMainTime() -> Double {
        let currentTimeIntervalInMilliSecond = Date().timeIntervalSince1970 * 1000.0
        var procInfo = kinfo_proc()
        let pid = ProcessInfo.processInfo.processIdentifier
        var cmd: [Int32] = [CTL_KERN, KERN_PROC, KERN_PROC_PID, pid]
        var size = MemoryLayout.stride(ofValue: procInfo)
        // Retrieve information of current process
        if sysctl(&cmd, UInt32(cmd.count), &procInfo, &size, nil, 0) == 0 {

pofat

# Add these in your Podfile (available for CocoaPods v1.7.x+)

# Replace with any Pods that you want to keep dynamically linked
keep_dynamically_linked = ['RxCocoa', 'RxSwift']

target 'YourApp' do
    # all you pods here...
end

pofat

/*
 * Note: You need to build this script before use
 * Usage:
 *       1. Build by `swfitc scan_unused_selectors.swift`
 *       2. Run by `./scan_unused_selectors /path/to/yourMachO`
 * 
 * How to locate MachO of your APP (`/path/to/yourMachO` in above example)? In your Xcod project navigator, you can find a folder `Products`
 * In that folder you can see your app (after any build) and right click on it -> "Show In Finder"
 * You can get your APP's location by drag it into your terminal. Say it's "/path/to/MyApp.app", your MachO path would be "/path/to/MyApp.app/MyApp"
 */

pofat

import Foundation
import UIKit

UIApplicationMain(CommandLine.argc, CommandLine.unsafeArgv, NSStringFromClass(UIApplication.self), NSStringFromClass(AppDelegate.self))

// Remeber to comment or remove `@UIApplicationMain` in your AppDelegate.swift

pofat

import Foundation

// Time Complexity: O(N), N stands for the level of key path
extension Dictionary where Key == String {
    subscript(keyPath keyPath: String) -> Any? {
        get {
            guard !keyPath.isEmpty else { return nil }
            var value: Any? = self
            for key in keyPath.components(separatedBy: ".") {
                if let node = (result as? [Key: Any])?[key] {

pofat

enum Either<A, B> {
    case left(A)
    case right(B)
}

extension Either: Decodable where A: Decodable, B: Decodable {
    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        if let a = try? container.decode(A.self) {
            self = .left(a)

pofat

Keybase proof

I hereby claim:

• I am pofat on github.
• I am pofat (https://keybase.io/pofat) on keybase.
• I have a public key ASDG9WSBfhua2AKTJqJhSDqdAuCPFwSEfVnVlhryt9fTVQo

To claim this, I am signing this object:

pofat

// 想像以下 function 定義在某一個 module 裡，外部無法決定也不依賴具體的型別 (此 func 你可以呼叫但裡面實作看不到）
func getIterator() -> some IteratorProtocol {
    var state = (0, 1)
    return MyAnyIterator { () -> Int in
        let upcomingNumber = state.0
        state = (state.1, state.0 + state.1)
        return upcomingNumber
    }
}

pofat

// 利用 init with closure 來自動代入 `Element` 真實的型別，而不是直接用 <某型別> 的方式來指定
// 先宣告一個 generic struct
struct MyAnyIterator<Element> {
    // 內部使用的 Box ，裡面就是把 closure 存起來，本身也滿足  IteratorProtocol
    private class AnyIteratorBox<Element>: IteratorProtocol {
        typealias Base = () -> Element?
        private var _base: Base

        init(_ base: @escaping Base) {
            self._base = base

pofat

// 有 associatedtype 的 protocol
public protocol IteratorProtocol {
  associatedtype Element
  mutating func next() -> Element?
}

// 有 Self 的 protocol, Hashable 的 Self 來自所繼承的 Equatable
public protocol Hashable: Equatable {
  var hashValue: Int { get }
  func hash(into hasher: inout Hasher)