iOS Development-a summary of practical techniques & common delay methods (Oc/swift)

Summary of common delay methods

This paper lists four methods of delaying execution of a function and some differences. If the delay is 1 seconds, execute the following method.

-(void) Delaymethod {NSLog (@ "execute");}

1.performSelector Method:(There is no such method in Swift because this method is considered unsafe in swift)

[Self performselector: @selector (Delaymethod) withobject:nil afterdelay:1.0f];

This method requires that it must be executed in the main thread, otherwise it is not valid.
is a non-blocking method of execution,
The method for canceling execution is not found yet.

2. Timer: Nstimer

 1 [nstimer scheduledtimerwithtimeinterval:1.0f target:self selector: @selector (Delaymethod) Userinfo:nil Repeats:no];

This method requires that it must be executed in the main thread, otherwise it is not valid.
is a non-blocking method of execution,
The Nstimer class can be invalidate by the-(void) or cancel execution.

3. Sleep mode

[Nsthread sleepfortimeinterval:1.0f]; [Self delaymethod];

This method can be executed in both the main thread and the child thread.
is a blocking method of execution that is placed in a sub-thread to avoid jamming the interface
No method was found to cancel execution.

4.GCD Way

 1  double  delayinseconds = 1.0  ;  2  3  __block viewcontroller* bself = self;  4  5  dispatch_time_t poptime = Dispatch_time (Dispatch_time_now, (int64_t) (delayinseconds * nsec_per_sec));  6  void   8  9  [bself Delaymethod]; });

In this way, the executing thread can be selected in the parameter.
is a non-blocking method of execution,
No method was found to cancel execution.

How to implement in Swift

1.sleep

1 //Create a destination queue2Let Workingqueue = Dispatch_queue_create ("My_queue", nil)3 4 //Dispatched to the queue you just created, GCD is responsible for thread scheduling5 Dispatch_async (workingqueue) {6     //asynchronously in the Workingqueue7println"work hard")8Nsthread.sleepfortimeinterval (2)//simulate two seconds of execution time9 Ten Dispatch_async (Dispatch_get_main_queue ()) { One         //back to the main thread update UI Aprintln"end work, update UI") -     } -}

2.GCD

1 2.0 2 Let delay =3                          Int64 (Time * Double (nsec_per_sec)))4Dispatch_ After (delay, dispatch_get_main_queue ()) {5     println ("output after 2 seconds " )6 }

Wrap it up.

1 Import Foundation2 3Typealias Task = (cancel:bool) ()4 5Func Delay (Time:nstimeinterval, Task: ()), task? {6 7Func Dispatch_later (Block: ()()) {8 Dispatch_after (9 Dispatch_time (Ten Dispatch_time_now, OneInt64 (Time *Double (NSEC_PER_SEC))), A dispatch_get_main_queue (), - block) -     } the  -var closure:dispatch_block_t? =Task -var result:task? -  +Let Delayedclosure:task = { -Cancelinch +         ifLet internalclosure =Closure { A             if(Cancel = =false) { at Dispatch_async (Dispatch_get_main_queue (), internalclosure); -             } -         } -Closure =Nil -result =Nil -     } in  -result =delayedclosure to  + Dispatch_later { -         ifLet delayedclosure =Result { theDelayedclosure (Cancel:false) *         } $     }Panax Notoginseng  -     returnresult; the } +  AFunc Cancel (task:task?) { theTask? (Cancel:true) +}

Use:

• let task = delay(5) { println("拨打 110") }// 仔细想一想..// 还是取消为妙..cancel(task)

iOS Development-a summary of practical techniques & common delay methods (Oc/swift)