Alamofire http json 请求块 ui [英] Alamofire http json request block ui
问题描述
我一直在创建一个从 JSON 脚本中检索对象的函数.为此,我选择使用 alamofire 进行异步请求,使用 swiftyJSON 进行轻松解析.但是我似乎对它阻止 UI 有问题?当它是异步请求时怎么会这样?我是否需要在单独的线程上运行它或者可能的解释是什么?
I've been creating a function which retrieve objects from a JSON script. I've chosen for this to use alamofire for async request and swiftyJSON for easy parsing. However i seem to have a problem with it blocking the UI? How come it does that when it is async request? Do i need to run it on a separate thread or what could the explanation be?
基本上我所说的阻塞 UI 的意思是在下面的函数执行完成之前它不会对其他按钮做出反应.
Basically what i mean by blocking UI is that it does not react on other buttons before the below function is finished executing.
func getRecent() {
var url = "http://URL/recent.php?lastid=(lastObjectIndex)&limit=(numberOfRecordsPerAPICall)"
isApiCalling = true
request(.GET, url, parameters: nil)
.response { (request, response, data, error) in
if error == nil {
let data: AnyObject = data!
let jsonArray = JSON(data: data as! NSData)
if jsonArray.count < self.numberOfRecordsPerAPICall {
self.recentCount = 0
self.tableVIew.tableFooterView = nil
} else {
self.recentCount = jsonArray.count
self.tableVIew.tableFooterView = self.footerView
}
for (key: String, subJson: JSON) in jsonArray {
// Create an object and parse your JSON one by one to append it to your array
var httpUrl = subJson["image_url"].stringValue
let url = NSURL(string: httpUrl)
let data = NSData(contentsOfURL: url!)
if UIImage(data: data!) != nil {
// Create an object and parse your JSON one by one to append it to your array
var newNewsObject = News(id: subJson["id"].intValue, title: subJson["title"].stringValue, link: subJson["url"].stringValue, imageLink: UIImage(data: data!)!, summary: subJson["news_text"].stringValue, date: self.getDate(subJson["date"].stringValue))
self.recentArray.append(newNewsObject)
}
}
self.lastObjectIndex = self.lastObjectIndex + self.numberOfRecordsPerAPICall
self.isApiCalling = false
self.tableVIew.reloadData()
self.refreshControl?.endRefreshing()
}
}
}
推荐答案
响应闭包在主线程上执行.如果您在那里进行 JSON 解析(并且您有大量数据),它将阻塞主线程一段时间.
The response closure is executed on the main thread. If you are doing your JSON parsing there (and you have a large amount of data) it will block the main thread for a while.
在这种情况下,您应该使用 dispatch_async
进行 JSON 解析,并且只有在您完成后才更新主线程.
In that case, you should use dispatch_async
for the JSON parsing and only when you are completed update the main thread.
像这样进行解析
func getRecent() {
var url = "http://URL/recent.php?lastid=(lastObjectIndex)&limit=(numberOfRecordsPerAPICall)"
isApiCalling = true
request(.GET, url, parameters: nil)
.response { (request, response, data, error) in
if error == nil {
let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
dispatch_async(dispatch_get_global_queue(priority, 0)) {
// Parse stuff here
let data: AnyObject = data!
let jsonArray = JSON(data: data as! NSData)
if jsonArray.count < self.numberOfRecordsPerAPICall {
self.recentCount = 0
self.tableVIew.tableFooterView = nil
} else {
self.recentCount = jsonArray.count
self.tableVIew.tableFooterView = self.footerView
}
for (key: String, subJson: JSON) in jsonArray {
// Create an object and parse your JSON one by one to append it to your array
var httpUrl = subJson["image_url"].stringValue
let url = NSURL(string: httpUrl)
let data = NSData(contentsOfURL: url!)
if UIImage(data: data!) != nil {
// Create an object and parse your JSON one by one to append it to your array
var newNewsObject = News(id: subJson["id"].intValue, title: subJson["title"].stringValue, link: subJson["url"].stringValue, imageLink: UIImage(data: data!)!, summary: subJson["news_text"].stringValue, date: self.getDate(subJson["date"].stringValue))
self.recentArray.append(newNewsObject)
}
}
dispatch_async(dispatch_get_main_queue()) {
// Update your UI here
self.lastObjectIndex = self.lastObjectIndex + self.numberOfRecordsPerAPICall
self.isApiCalling = false
self.tableVIew.reloadData()
self.refreshControl?.endRefreshing()
}
}
}
}
}
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