John_Fighting的博客

一次性任务在程序的整个生命周期只运行一次且一次(one and only once) dispatch_once(—, ^block {})#import "ViewController.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad { [super viewDidLo

GCD把多个任务(下载图片)打包成一个组Group, 调用group_notify, 可以做其他的事情.#import "ViewController.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; //全局队列+异步执行

选择: 全局队列+异步执行 UIButton + UIImageView 图片的地址 (网址)URL(Uniform Resource Locator) http:/xx/xxx/ss.png#import "ViewController.h"@interface ViewController ()@property (weak, nonatomic) IBOutlet UIImageVie

串行队列串行队列同步执行- (IBAction)SerialQueueSync:(id)sender { //1.创建串行队列 dispatch_queue_t queue = dispatch_queue_create("FirstSerialQueue", DISPATCH_QUEUE_SERIAL); //2.提交任务到队列中(block) //同步执行任务