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，它是如何做到的？我是否需要在单独的线程上运行它或者解释是什么？
基本上，我所说的阻塞 UI 的意思是，在以下函数完成执行之前，它不会对其他按钮使用react。
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()
}
}
}
最佳答案
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)，它会阻塞主线程一段时间。
在这种情况下，您应该使用 dispatch_async 进行 JSON 解析，并且只有在完成后才更新主线程。
像这样做你的解析
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()
}
}
}
}
}
关于ios - Alamofire http json 请求 block ui，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30050349/