Last time in the post about Operation And OperaionQueue we discussed how to create and use Operation inside closure.
Using closure is an option if there is a simple task to do. However, if there is a more complex task it’s worth considering creating a custom operation class.
Operation is an open class introduced in iOS 2.0.
Let’s say you want to make a custom class to handle the same save operation as in the previous example.
class FileSaver: Operation {
let fileName: String
init(fileName: String) {
self.fileName = fileName
}
override func main() {
saveFile()
}
func saveFile() {
print(“File name: \(fileName)“)
}
}
To execute code in the background you need to override the main function which will be executed in a background thread.
To check if it works to use the same code as previously. There is one difference that there is creating a new FileSaver instance instead of using closure.
let queue = OperationQueue()
let files = [“photosUrl”, “musicUrl”, “moviesUrl”]
for file in files {
queue.addOperation(FileSaver(fileName: file))
}
Output
File name: photosUrl
File name: musicUrl
File name: moviesUrl
