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public extension CGImage {

    func bitmapImage() -> CGImage? {
        
        guard
            let colorSpace = colorSpace,
            let context = CGContext(
                data: nil,
                width: width,
                height: height,

guzhenhuaGitHub

import UIKit

// According to article by John Sundell
// https://www.swiftbysundell.com/articles/caching-in-swift/

final class Cache<Key: Hashable, Value> {
    private let wrapped = NSCache<WrappedKey, Entry>()
    private let dateProvider: () -> Date
    private let entryLifetime: TimeInterval
    private let keyTracker = KeyTracker()

guzhenhuaGitHub

/// 解决视图右滑与系统右滑返回上级页面手势冲突
protocol PopGestureConflictProtocol {
}

extension UIViewController: PopGestureConflictProtocol {}
extension PopGestureConflictProtocol where Self: UIViewController {

    /// 处理scrollView和系统右滑返回手势的冲突
    ///
    ///    虽然self可能是某个UIViewController的子视图，但是不用管它。直接处理navigationController的手势冲突就行了

guzhenhuaGitHub

public extension UIImage {
    /// 圆角图片
    func roundCornerImage(withCornerRadius cornerRadius: CGFloat) -> UIImage? {
        // 开关图形上下文
        UIGraphicsBeginImageContext(size)
        defer { UIGraphicsEndImageContext() }
        // 获取图形上下文
        let context = UIGraphicsGetCurrentContext()
        // 带圆角的长方形贝塞尔曲线
        let roundedRect = CGRect(x: 0, y: 0, width: size.width, height: size.height)

guzhenhuaGitHub

extension Sequence {
    func map<T>(_ keyPath: KeyPath<Element, T>) -> [T] {
        return map { $0[keyPath: keyPath] }
    }
}

extension Sequence {
    func sorted<T: Comparable>(by keyPath: KeyPath<Element, T>) -> [Element] {
        return sorted { a, b in
            return a[keyPath: keyPath] < b[keyPath: keyPath]

guzhenhuaGitHub

alias cow=fortune | cowsay | lolcat

guzhenhuaGitHub

enum PasswordRule {
    enum CharacterClass {
        case upper, lower, digits, special, asciiPrintable, unicode
        case custom(Set<Character>)
    }

    case required(CharacterClass)
    case allowed(CharacterClass)
    case maxConsecutive(UInt)
    case minLength(UInt)

guzhenhuaGitHub

/* 将Lodash的方法注入到Vue的filter中 */
_.each(_, (v, k) => {
  if (_.isFunction(v)) {
    Vue.filter('_' + k, (input, args) => {
      return v.apply(_, _.flatten([[input], args]))
    })
  }
})

guzhenhuaGitHub

extension Collection {
    func eachConsecutive(_ size: Int) -> [[Element]] {
        let droppedIndices = indices.dropFirst(size - 1)
        return zip(indices, droppedIndices)
            .map {
                return Array(self[$0...$1])
            }
    }
}

guzhenhuaGitHub

extension Array {
    func eachSlice(_ step: Int) -> [[Element]] {
        return stride(from: 0, through: count, by: step)
            .lazy
            .map { from in
                let to = Swift.min(from + step, count)
                return (from..<to)
                    .lazy
                    .map { [self[$0]] }
                    .reduce([], +)