// 有没有更简洁的实现方式？！ public class CustomArray<Element> { let queue = DispatchQueue(label: "com.xq.customarray", attributes: .concurrent) var array: [Element] init() { array = [Element]() } init(_ ary: [Element]) { array = ary } } extension CustomArray { var count: Int { var result = 0 queue.sync { result = self.array.count } return result } func filter(_ isIncluded: (Element) -> Bool) -> CustomArray<Element> { var result = [Element]() queue.sync { result = self.array.filter(isIncluded) } return CustomArray(result) } func append(_ newElement: Element){ //并发+异步写入（barrier机制） queue.async(flags: .barrier) { self.array.append(newElement) } } func joined(separator: String = "") -> String { var str = "" queue.sync { if let ary = array as? [String] { str = ary.joined(separator: ",") } } return str } func map<T>(_ transform : @escaping (Element) -> T) -> CustomArray<T> { let n = self.count guard n > 0 else { return CustomArray<T>() } let result: CustomArray<T> = CustomArray<T>() DispatchQueue.concurrentPerform(iterations: n) { (i) in result.append(transform(array[i])) } return result } } let employee = ["neal", "s", "stu", "j", "rich", "bob", "aiden", "j", "ethan", "liam", "mason", "noah", "lucas", "jacob", "jack"] let resultNames0 = employee.filter{ $0.count > 1 } .map{ $0.capitalized } .joined(separator: ",") let resultNames1 = CustomArray(employee).filter { $0.count > 1 } .map{ $0.capitalized } .joined(separator: ",") print("\(resultNames0.count), \(resultNames0)") print("\(resultNames1.count), \(resultNames1)")

没有没比较全的高阶函数总结，map， filter， reduce，foreach等在哪里可以找到

capitalized 我这也没有，提示Value of type 'String' has no member 'capitalized'

Value of type 'String' has no member 'capitalized' 报错了，请问老师如何解决？

和OC一样，对线程进行加锁，可进行安全访问，对吗

老师，有个问题，这里map、filter等会循序单词数组吗?这里的例子是不是会循序三次才计算出最后的结果？