函数与dataTask返回一个值

Question

我不想检查我的url statusCode是否等于200,如果statusCode等于200,我创建了一个返回布尔函数的函数,我正在使用dataTask,但我不知道如何返回一个值:

class func checkUrl(urlString: String) -> Bool{

    let urlPath: String = urlString
    var url: NSURL = NSURL(string: urlPath)!
    var request: NSURLRequest = NSURLRequest(url: url as URL)
    var response: URLResponse?

    let session = Foundation.URLSession.shared


    var task = session.dataTask(with: request as URLRequest, completionHandler: {(data, response, error) in
        if let error = error {
            print(error)
        }

        if let data = data{
            print("data =\(data)")
        }
        if let response = response {
            print("url = \(response.url!)")
            print("response = \(response)")
            let httpResponse = response as! HTTPURLResponse
            print("response code = \(httpResponse.statusCode)")

            if httpResponse.statusCode == 200{
                return true
            } else {
                return false
            }
        }
    })
    task.resume()
}

返回if else返回错误:

void函数中出现意外的非void返回值

Answer 1

为了返回值,你应该使用块.尝试声明你的功能:

class func checkUrl(urlString: String, finished: ((isSuccess: Bool)->Void) {

    let urlPath: String = urlString
    var url: NSURL = NSURL(string: urlPath)!
    var request: NSURLRequest = NSURLRequest(url: url as URL)
    var response: URLResponse?

    let session = Foundation.URLSession.shared


    var task = session.dataTask(with: request as URLRequest, completionHandler: {(data, response, error) in
        if let error = error {
            print(error)
        }

        if let data = data{
            print("data =\(data)")
        }
        if let response = response {
            print("url = \(response.url!)")
            print("response = \(response)")
            let httpResponse = response as! HTTPURLResponse
            print("response code = \(httpResponse.statusCode)")

            if httpResponse.statusCode == 200{
                finished(isSuccess: true)                
            } else {
                finished(isSuccess: false) 
            }
        }
    })
    task.resume()
}

然后像这样调用它:

checkUrl("http://myBestURL.com", finished { isSuccess in
// Handle logic after return here
})

希望这会有所帮助.

Answer 2

考虑semaphore是否要保留原始的返回模式。

func checkUrl(urlString: String) -> Bool {
    if let url = URL(string: fileUrl) {
        var result: Bool!

        let semaphore = DispatchSemaphore(value: 0)  //1. create a counting semaphore

        let session = URLSession.shared
        session.dataTask(with: url, completionHandler: { (data, response, error) in
            result = true  //or false in case
            semaphore.signal()  //3. count it up
        }).resume()

        semaphore.wait()  //2. wait for finished counting

        return result
    }

    return false
}