同步任务,异步任务
同步:不开启子线程
异步:一定开启子线程
并行,串行:
并行:多个任务同时执行
串行:一个个执行
并行+异步:开启多个线程
并行+同步:在一个线程内执行多个任务
串行+异步:需要开启子线程
串行+同步:不需要开启子线程
使用 GCD 步骤:1.制定任务 2.添加到队列
- ViewController.m
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
//GCD---队列形式进行操作
//异步
[self asyncGlobalQueue];
//同步
[self syncGlobalQueue];
[self loadData];
}
#pragma mark --- 使用异步方法添加到队列中
-(void)asyncGlobalQueue{
//获取全局并发队列
//获取全局并发队列
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
//添加到任务队列中
//异步
dispatch_async(queue, ^{
NSLog(@"1:%@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"2:%@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"3:%@",[NSThread currentThread]);
});
}
#pragma mark --- 串行队列
-(void)sayncSerialQueue{
//创建
dispatch_queue_t queue = dispatch_queue_create("hello", NULL);
//任务
dispatch_async(queue, ^{
NSLog(@"1:%@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"2:%@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"3:%@",[NSThread currentThread]);
});
}
#pragma mark --- 使用同步方法添加到队列中
-(void)syncGlobalQueue{
//并发
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
//添加任务到队列
dispatch_sync(queue, ^{
NSLog(@"1:%@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"2:%@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"3:%@",[NSThread currentThread]);
});
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(void)test
{
//执行任务: GCD 中有两个执行任务函数
//同步
//1.dispatch_queue_t:队列
//2.任务
// dispatch_sync(<#dispatch_queue_t _Nonnull queue#>, ^{
// <#code#>
// })
//异步:
// dispatch_sync(<#dispatch_queue_t _Nonnull queue#>, <#^(void)block#>)
}
//https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1497420262955&di=31fe0a09ecb071382b935112e90d1f89&imgtype=0&src=http%3A%2F%2Fv1.qzone.cc%2Fskin%2F201511%2F29%2F09%2F55%2F565a5b0d64410783.jpg%2521600x600.jpg
-(void)loadData
{
NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionTask *test = [session dataTaskWithURL:[NSURL URLWithString:@"url"]completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
if (error == nil) {
dispatch_async(dispatch_get_main_queue(), ^{
//更新 UI 事件
});
}
}];
//启动任务
[test resume];
}
@end
