swift dispatch queue
extension DispatchQueue {
static func background(delay: Double = 0.0, background: (()->Void)? = nil, completion: (() -> Void)? = nil) {
DispatchQueue.global(qos: .background).async {
background?()
if let completion = completion {
DispatchQueue.main.asyncAfter(deadline: .now() + delay, execute: {
completion()
})
}
}
}
}
DispatchQueue.background(delay: 3.0, background: {
// do something in background
}, completion: {
// when background job finishes, wait 3 seconds and do something in main thread
})
DispatchQueue.background(background: {
// do something in background
}, completion:{
// when background job finished, do something in main thread
})
DispatchQueue.background(delay: 3.0, completion:{
// do something in main thread after 3 seconds
})