NSOperationQueue 的 maxConcurrentOperationCount 的默认值

NSOperationQueue 是 iOS 开发中常用的多线程编程工具之一。它可以用来管理和调度多个操作（Operation），实现并发执行任务的效果。在我们创建 NSOperationQueue 对象时，可以通过设置 maxConcurrentOperationCount 属性来控制同时执行的最大操作数。

swift
import Foundation
class MyOperation: Operation {
    override func main() {
        print("Operation started")
        sleep(1)
        print("Operation finished")
    }
}
let queue = OperationQueue()
for i in 1...5 {
    let operation = MyOperation()
    queue.addOperation(operation)
}
queue.waitUntilAllOperationsAreFinished()
print("All operations finished")

swift
import Foundation
class MyOperation: Operation {
    let name: String
    
    init(name: String) {
        self.name = name
    }
    
    override func main() {
        print("\(name) started")
        sleep(1)
        print("\(name) finished")
    }
}
let queue = OperationQueue()
queue.maxConcurrentOperationCount = 1
for i in 1...5 {
    let operation = MyOperation(name: "Operation \(i)")
    queue.addOperation(operation)
}
queue.waitUntilAllOperationsAreFinished()
print("All operations finished")