所以我有一个请求任务，在其中，我有另一个请求任务的循环。我想完成循环请求任务，然后继续完成另一个任务。
let dispatchGroup = DispatchGroup()
override func viewDidLoad() {
super.viewDidLoad()
tableView.reloadData()
fetchData()
dispatchGroup.notify(queue: .main) {
self.tableView.reloadData()
}
}
func fetchData() {
var movies: String?
dispatchGroup.enter()
print("Enter fetchData")
let task = session.dataTask(with: url) { data, response, error in
if error != nil || data == nil {
print("Client error!")
return
}
guard let response = response as? HTTPURLResponse, (200...299).contains(response.statusCode) else {
print("Server error!")
return
}
guard let mime = response.mimeType, mime == "application/json" else {
print("Wrong MIME type!")
return
}
do {
let json = try JSONSerialization.jsonObject(with: data!, options: []) as? [String : Any]
if let result = json?["results"] as? Array<Dictionary<String, Any>> {
for results in result {
self.char = StarWarsData.init(name: results["name"] as! String, height: results["height"] as! String, mass: results["mass"] as! String, gender: results["gender"] as! String, birthyear: results["birth_year"] as! String, film: results["films"] as! [String])
let name = self.char.name
let height = self.char.height
let mass = self.char.mass
let gender = self.char.gender
let birthyear = self.char.birthyear
let charFilms = self.char.film
for theFilms in charFilms {
self.fetchFilms(films: theFilms) { (filmNames) in
movies = filmNames
print(movies!)
}
}
let item = StarWarsData(name: name, height: height, mass: mass, gender: gender, birthyear: birthyear, film: charFilms)
self.dataArray.append(item)
self.dataNames.append(name)
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
}
}catch {
print("JSON error: \(error.localizedDescription)")
}
print("Leaving fetchData")
self.dispatchGroup.leave()
}
task.resume()
}
func fetchFilms(films: String, taskCallBack: @escaping (String) -> ()) {
let url = URL(string: films)!
var filmsArr: [String] = []
var item: String!
var joinItem: String!
dispatchGroup.enter()
print("Enter fetchFilms")
let task = self.session.dataTask(with: url, completionHandler: { (data, response, error) -> Void in
if error != nil || data == nil {
print("Client error!")
return
}
guard let response = response as? HTTPURLResponse, (200...299).contains(response.statusCode) else {
print("Server error!")
return
}
guard let mime = response.mimeType, mime == "application/json" else {
print("Wrong MIME type!")
return
}
do {
let json = try JSONSerialization.jsonObject(with: data!, options: []) as? [String : Any]
if let results = json?["title"] as? String {
for results in results {
item = String(results)
filmsArr.append(item)
}
joinItem = filmsArr.joined(separator: "")
taskCallBack(joinItem)
}
}catch {
print("JSON error: \(error.localizedDescription)")
}
print("Leaving fetchFilms")
self.dispatchGroup.leave()
})
task.resume()
}
因此，检查打印报表，您将了解我想要的内容。
这是我的输出。
Enter fetchData
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Leaving fetchData
A New Hope
Leaving fetchFilms
The Empire Strikes Back
Leaving fetchFilms
Return of the Jedi
Leaving fetchFilms
The Force Awakens
Leaving fetchFilms
Revenge of the Sith
Leaving fetchFilms
The Empire Strikes Back
Leaving fetchFilms
The Phantom Menace
Leaving fetchFilms
Attack of the Clones
Leaving fetchFilms
Revenge of the Sith
Leaving fetchFilms
The Phantom Menace
Leaving fetchFilms
Notify table reloaded
我只是想这样：
Enter fetchData
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
Enter fetchFilms
A New Hope
Leaving fetchFilms
The Empire Strikes Back
Leaving fetchFilms
Return of the Jedi
Leaving fetchFilms
The Force Awakens
Leaving fetchFilms
Revenge of the Sith
Leaving fetchFilms
The Empire Strikes Back
Leaving fetchFilms
The Phantom Menace
Leaving fetchFilms
Attack of the Clones
Leaving fetchFilms
Revenge of the Sith
Leaving fetchFilms
The Phantom Menace
Leaving fetchFilms
Leaving fetchData
Notify table reloaded
我想以某种方式在打印语句
Leaving fetchData之前暂停任务，并完成func fetchFilms的整个过程，然后继续打印语句Leaving fetchData。实际上func fetchData()在func fetchFilms结束之前就完成了，我不拍我想要的电影。顺便说一句，print(movies!)声明给了我电影，但是为时已晚。 最佳答案
[编辑]：为突出媒体发布的主要思想，还删除了信号灯，但并不是真正的敏捷风格。
如果希望在另一个函数调用之前完成一个函数（特别是在数据任务的情况下），则可以使用“操作”。
我找到了一个更好的文章来指导您如何实现它。
https://medium.com/@oleary.audio/simultaneous-asynchronous-calls-in-swift-9c1f5fd3ea32
关于ios - 等到swift for loop网络请求完成执行( native ，不使用任何框架)，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/58365724/