Swift 队列的创建

swift 创建的队列默认为串行队列

        let queue = DispatchQueue(label: "hahha")
//        let queue = DispatchQueue(label: "haha", attributes: .concurrent)
        
        for _ in 1...10 {
            queue.async {
                print("111---" + "\(Thread.current)")
            }
        }
        for _ in 1...10 {
            queue.async {
                print("222---" + "\(Thread.current)")
            }
        }
        for _ in 1...10 {
            queue.async {
                print("333---" + "\(Thread.current)")
            }
        }

运行结果：

111---<NSThread: 0x600000279b40>{number = 3, name = (null)}
111---<NSThread: 0x600000279b40>{number = 3, name = (null)}
111---<NSThread: 0x600000279b40>{number = 3, name = (null)}
111---<NSThread: 0x600000279b40>{number = 3, name = (null)}
111---<NSThread: 0x600000279b40>{number = 3, name = (null)}
111---<NSThread: 0x600000279b40>{number = 3, name = (null)}
111---<NSThread: 0x600000279b40>{number = 3, name = (null)}
111---<NSThread: 0x600000279b40>{number = 3, name = (null)}
111---<NSThread: 0x600000279b40>{number = 3, name = (null)}
111---<NSThread: 0x600000279b40>{number = 3, name = (null)}
222---<NSThread: 0x600000279b40>{number = 3, name = (null)}
222---<NSThread: 0x600000279b40>{number = 3, name = (null)}
222---<NSThread: 0x600000279b40>{number = 3, name = (null)}
222---<NSThread: 0x600000279b40>{number = 3, name = (null)}
222---<NSThread: 0x600000279b40>{number = 3, name = (null)}
222---<NSThread: 0x600000279b40>{number = 3, name = (null)}
222---<NSThread: 0x600000279b40>{number = 3, name = (null)}
222---<NSThread: 0x600000279b40>{number = 3, name = (null)}
222---<NSThread: 0x600000279b40>{number = 3, name = (null)}
222---<NSThread: 0x600000279b40>{number = 3, name = (null)}
333---<NSThread: 0x600000279b40>{number = 3, name = (null)}
333---<NSThread: 0x600000279b40>{number = 3, name = (null)}
333---<NSThread: 0x600000279b40>{number = 3, name = (null)}