swift GCD 封装：喵神
虽然自己理解的一般，但是喵神已经写好封装，以后自己好好理解，感谢喵神~
import Foundation
typealias Task = (cancel : Bool) -> ()
func delay(time:NSTimeInterval, task:()->()) -> Task? {
func dispatch_later(block:()->()) {
dispatch_after(
dispatch_time(
DISPATCH_TIME_NOW,
Int64(time * Double(NSEC_PER_SEC))),
dispatch_get_main_queue(),
block)
}
var closure: dispatch_block_t? = task
var result: Task?
let delayedClosure: Task = {
cancel in
if let internalClosure = closure {
if (cancel == false) {
dispatch_async(dispatch_get_main_queue(), internalClosure);
}
}
closure = nil
result = nil
}
result = delayedClosure
dispatch_later {
if let delayedClosure = result {
delayedClosure(cancel: false)
}
}
return result;
}
func cancel(task:Task?) {
task?(cancel: true)
}
