ios - NSURLSessionConfiguration 和 NSMutableURLRequest 缓存策略的区别

Question

我正在使用代码:

let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()
configuration.requestCachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalCacheData
let session = NSURLSession(configuration: configuration)
let request = NSMutableURLRequest(URL: url)
request.cachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalCacheData
request.HTTPMethod = "POST"
request.HTTPBody = bodyData
let dataTask = session.dataTaskWithRequest(request) { (data: NSData?, response: NSURLResponse?, error: NSError?) in 
    //... 
}

我想知道这两者之间有什么区别，以及必须使用哪一个。

configuration.requestCachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalCacheData
request.cachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalCacheData

谢谢。

Answer 1

NSURLSessionConfiguration sets the properties at NSURLSession which can be overridden by NSURLRequest object.

正如这里的回答: https://stackoverflow.com/a/33316897/3238178