iOS Thread Development Summary

/*

The method name determines whether a new thread (Async,sync) is turned on, and the queue type (global queue, serial queue) determines how many threads to open

1. Fast thread invocation

* Turn on background threads to perform tasks

[Self performselectorinbackground: @selector (Test) Withobject:nil];

* Go back to the main thread to perform the task

[Self Performselectoronmainthread: @selector (setimage:) withobject:image Waituntildone:yes];

2.GCD: Dependent queue execution

1> queue Type

* Global Queue

* All tasks added to the global queue are executed concurrently (concurrently, multiple threads may be turned on)

* Dispatch_get_global_queue

* Serial Queue

* All tasks added to the serial queue are executed sequentially (one thread is open)

* Dispatch_queue_create ("Myqueue", 0);

* Home Row

* All tasks added to the main queue are executed in the main thread (not related to the method name)

* Dispatch_get_main_queue

2> synchronous or asynchronous, depending on the method name (does not affect the home column, affects the global queue, serial queue)

* Sync: Dispatch_sync, perform task on current thread, not open new thread

* Async: Dispatch_async, performs tasks on other threads, opens new thread

3.nsoperation\nsoperationqueue

1> Use steps

* Create Nsoperation

* Add Nsoperation to Nsoperationqueue

2> Advantages

* More Object-oriented

* Can control the maximum number of concurrent Maxconcurrentoperationcount

* Add dependencies between tasks (operation) adddependency

*/

#import "XMQViewController.h"

@interface Xmqviewcontroller ()

{

Nsoperationqueue *_queue;

}

@end

@implementation Xmqviewcontroller

-(void) viewdidload

{

[Super Viewdidload];

_queue = [[Nsoperationqueue alloc] init];

Control maximum concurrency and execute up to 3 threads at the same time

_queue.maxconcurrentoperationcount = 3;

Back to main thread

[Self test];

Thread Monitoring

[Self gcd_group];

GCD thread Dependency

[Self gcd_barrier];

Loop execution

[Self gcd_apply];

Global queue

dispatch_queue_t queue = Dispatch_get_global_queue (Dispatch_queue_priority_default, 0);

Serial queue

dispatch_queue_t queue2 = dispatch_queue_create ("Myqueue", 0);

Dispatch_async (queue, ^{//time-consuming operation

NSLog (@ "This is an asynchronous thread---%@", [Nsthread CurrentThread]);

});

}

-(ibaction) click

{

Nsoperation *operation = [Nsblockoperation blockoperationwithblock:^{

NSLog (@ "Operation---%@", [Nsthread CurrentThread]);

}];

Nsoperation *operation2 = [Nsblockoperation blockoperationwithblock:^{

NSLog (@ "Operation2---%@", [Nsthread CurrentThread]);

}];

This method is executed by default on the main thread

[Operation start];

The join queue executes on an asynchronous thread

[_queue addoperation:operation];

[_queue Addoperation:operation2];

Set thread dependency (Operation2 depends on operation,operation execution to execute operation2)

[Operation Adddependency:operation2];

}

Defer execution of a thread

-(Ibaction) Click2

{

Global queue

dispatch_queue_t queue = Dispatch_get_global_queue (Dispatch_queue_priority_default, 0);

Serial queue

dispatch_queue_t queue2 = dispatch_queue_create ("Myqueue", 0);

Double delayinseconds = 5.0;

dispatch_time_t delayinnanoseconds =dispatch_time (Dispatch_time_now, delayinseconds * NSEC_PER_SEC);

Dispatch_after (Delayinnanoseconds, Queue2, ^{

NSLog (@ "deferred execution");

});

}

Dispatch_group_async (asynchronous method) can be implemented to listen to a set of tasks are completed, and then be notified to perform other actions (such as notifying users to download, display UI, etc.)

-(void) Gcd_group

{

dispatch_queue_t queue = Dispatch_get_global_queue (Dispatch_queue_priority_default, 0);

dispatch_group_t group = Dispatch_group_create ();

Dispatch_group_async (group, queue, ^{

[Nsthread sleepfortimeinterval:1];

NSLog (@ "group1");

});

Dispatch_group_async (group, queue, ^{

[Nsthread Sleepfortimeinterval:2];

NSLog (@ "group2");

});

Dispatch_group_async (group, queue, ^{

[Nsthread Sleepfortimeinterval:3];

NSLog (@ "Group3");

});

Dispatch_group_notify (Group, Dispatch_get_main_queue (), ^{

NSLog (@ "UpdateUI");

});

}

Dispatch_barrier_async is executed after the execution of the previous task is completed, and subsequent tasks must wait until it finishes executing

-(void) Gcd_barrier

{

dispatch_queue_t queue = dispatch_queue_create ("Myqueue", dispatch_queue_concurrent);

Dispatch_async (Queue, ^{

[Nsthread Sleepfortimeinterval:2];

NSLog (@ "dispatch_async1");

});

Dispatch_async (Queue, ^{

[Nsthread Sleepfortimeinterval:4];

NSLog (@ "DISPATCH_ASYNC2");

});

Dispatch_barrier_async (Queue, ^{

NSLog (@ "Dispatch_barrier_async");

[Nsthread Sleepfortimeinterval:4];

});

Dispatch_async (Queue, ^{

[Nsthread Sleepfortimeinterval:2];

NSLog (@ "dispatch_async3");

});

}

Dispatch_apply executes a code fragment n times

-(void) gcd_apply

{

dispatch_queue_t queue = dispatch_queue_create ("Myqueue", Dispatch_queue_priority_default);

dispatch_apply, queue, ^ (size_t index) {

NSLog (@ "loop execution 10 times");

});

}

Back to main thread

-(void) test

{

UIImage *image = nil;

[Self Performselectoronmainthread: @selector (setimage:) withobject:image Waituntildone:yes];

Dispatch_async (Dispatch_get_main_queue (), ^{

NSLog (@ "Update UI interface---%@", [Nsthread CurrentThread]);

});

}

@end