GCD的基本使用:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {// dispatch_sync : 同步，不具備開啟線程的能力// dispatch_async : 異步，具備開啟線程的能力// 并發(fā)隊(duì)列 ：多個(gè)任務(wù)可以同時(shí)執(zhí)行// 串行隊(duì)列 ：一個(gè)任務(wù)執(zhí)行完后，再執(zhí)行下一個(gè)任務(wù)// 獲得全局的并發(fā)隊(duì)列dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);// 將 任務(wù) 添加 全局隊(duì)列 中去 異步 執(zhí)行dispatch_async(queue, ^{NSLog(@"-----下載圖片1---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片2---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片3---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片4---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片5---%@", [NSThread currentThread]);}); }

GCD中隊(duì)列的使用:

// dispatch_sync : 同步，不具備開啟線程的能力 // dispatch_async : 異步，具備開啟線程的能力// 并發(fā)隊(duì)列 ：多個(gè)任務(wù)可以同時(shí)執(zhí)行 // 串行隊(duì)列 ：一個(gè)任務(wù)執(zhí)行完后，再執(zhí)行下一個(gè)任務(wù)// Foundation : OC // Core Foundation : C語言 // Foundation和Core Foundation框架的數(shù)據(jù)類型可以互相轉(zhuǎn)換的//NSString *str = @"123"; // Foundation //CFStringRef str2 = (__bridge CFStringRef)str; // Core Foundation //NSString *str3 = (__bridge NSString *)str2; // CFArrayRef ---- NSArray // CFDictionaryRef ---- NSDictionary // CFNumberRef ---- NSNumber// Core Foundation中手動創(chuàng)建的數(shù)據(jù)類型，都需要手動釋放 // CFArrayRef array = CFArrayCreate(NULL, NULL, 10, NULL); // CFRelease(array); // // // CGPathRef path = CGPathCreateMutable(); // CGPathRetain(path); // // CGPathRelease(path); // CGPathRelease(path); /**凡是函數(shù)名中帶有create\copy\new\retain等字眼, 都應(yīng)該在不需要使用這個(gè)數(shù)據(jù)的時(shí)候進(jìn)行releaseGCD的數(shù)據(jù)類型在ARC環(huán)境下不需要再做releaseCF(Core Foundation)的數(shù)據(jù)類型在ARC\MRC環(huán)境下都需要再做release*/#import "HMViewController.h"@interface HMViewController ()@end@implementation HMViewController- (void)viewDidLoad {[super viewDidLoad];}- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {[self asyncSerialQueue]; }/*** async -- 并發(fā)隊(duì)列（最常用）* 會不會創(chuàng)建線程：會，一般同時(shí)開多條* 任務(wù)的執(zhí)行方式：并發(fā)執(zhí)行*/ - (void)asyncGlobalQueue {// 獲得全局的并發(fā)隊(duì)列dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);// 將 任務(wù) 添加 全局隊(duì)列 中去 異步 執(zhí)行dispatch_async(queue, ^{NSLog(@"-----下載圖片1---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片2---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片3---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片4---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片5---%@", [NSThread currentThread]);}); }/*** async -- 串行隊(duì)列（有時(shí)候用）* 會不會創(chuàng)建線程：會，一般只開1條線程* 任務(wù)的執(zhí)行方式：串行執(zhí)行（一個(gè)任務(wù)執(zhí)行完畢后再執(zhí)行下一個(gè)任務(wù)）*/ - (void)asyncSerialQueue {// 1.創(chuàng)建一個(gè)串行隊(duì)列dispatch_queue_t queue = dispatch_queue_create("cn.heima.queue", NULL);// 2.將任務(wù)添加到串行隊(duì)列中 異步 執(zhí)行dispatch_async(queue, ^{NSLog(@"-----下載圖片1---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片2---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片3---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片4---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片5---%@", [NSThread currentThread]);});// 3.非ARC，需要釋放創(chuàng)建的隊(duì)列 // dispatch_release(queue); }/*** async -- 主隊(duì)列(很常用)*/ - (void)asyncMainQueue {// 1.主隊(duì)列(添加到主隊(duì)列中的任務(wù)，都會自動放到主線程中去執(zhí)行)dispatch_queue_t queue = dispatch_get_main_queue();// 2.添加 任務(wù) 到主隊(duì)列中 異步 執(zhí)行dispatch_async(queue, ^{NSLog(@"-----下載圖片1---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片2---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片3---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片4---%@", [NSThread currentThread]);});dispatch_async(queue, ^{NSLog(@"-----下載圖片5---%@", [NSThread currentThread]);}); }/*** sync -- 主隊(duì)列(不能用---會卡死)*/ - (void)syncMainQueue {NSLog(@"syncMainQueue----begin--");// 1.主隊(duì)列(添加到主隊(duì)列中的任務(wù)，都會自動放到主線程中去執(zhí)行)dispatch_queue_t queue = dispatch_get_main_queue();// 2.添加 任務(wù) 到主隊(duì)列中 異步 執(zhí)行dispatch_sync(queue, ^{NSLog(@"-----下載圖片1---%@", [NSThread currentThread]);});dispatch_sync(queue, ^{NSLog(@"-----下載圖片2---%@", [NSThread currentThread]);});dispatch_sync(queue, ^{NSLog(@"-----下載圖片3---%@", [NSThread currentThread]);});NSLog(@"syncMainQueue----end--"); }/**-------------------------------------華麗的分割線-----------------------------------------------------**//*** sync -- 并發(fā)隊(duì)列* 會不會創(chuàng)建線程：不會* 任務(wù)的執(zhí)行方式：串行執(zhí)行（一個(gè)任務(wù)執(zhí)行完畢后再執(zhí)行下一個(gè)任務(wù)）* 并發(fā)隊(duì)列失去了并發(fā)的功能*/ - (void)syncGlobalQueue {// 獲得全局的并發(fā)隊(duì)列dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);// 將 任務(wù) 添加到 全局并發(fā)隊(duì)列 中 同步 執(zhí)行dispatch_sync(queue, ^{NSLog(@"-----下載圖片1---%@", [NSThread currentThread]);});dispatch_sync(queue, ^{NSLog(@"-----下載圖片2---%@", [NSThread currentThread]);});dispatch_sync(queue, ^{NSLog(@"-----下載圖片3---%@", [NSThread currentThread]);});dispatch_sync(queue, ^{NSLog(@"-----下載圖片4---%@", [NSThread currentThread]);});dispatch_sync(queue, ^{NSLog(@"-----下載圖片5---%@", [NSThread currentThread]);}); }/*** sync -- 串行隊(duì)列* 會不會創(chuàng)建線程：不會* 任務(wù)的執(zhí)行方式：串行執(zhí)行（一個(gè)任務(wù)執(zhí)行完畢后再執(zhí)行下一個(gè)任務(wù)）*/ - (void)syncSerialQueue {// 創(chuàng)建一個(gè)串行隊(duì)列dispatch_queue_t queue = dispatch_queue_create("cn.heima.queue", NULL);// 將 任務(wù) 添加到 串行隊(duì)列 中 同步 執(zhí)行dispatch_sync(queue, ^{NSLog(@"-----下載圖片1---%@", [NSThread currentThread]);});dispatch_sync(queue, ^{NSLog(@"-----下載圖片2---%@", [NSThread currentThread]);});dispatch_sync(queue, ^{NSLog(@"-----下載圖片3---%@", [NSThread currentThread]);});dispatch_sync(queue, ^{NSLog(@"-----下載圖片4---%@", [NSThread currentThread]);});dispatch_sync(queue, ^{NSLog(@"-----下載圖片5---%@", [NSThread currentThread]);}); }@end

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轉(zhuǎn)載于:https://www.cnblogs.com/ZMiOS/p/4924219.html

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