多线程在各种编程语言中都是难点,很多语言中实现起来很麻烦,objective-c虽然源于c,但其多线程编程却相当简单,可以与java相媲美。这篇文章主要从线程创建与启动、线程的同步与锁、线程的交互、线程池等等四个方面简单的讲解一下iphone中的多线程编程。 一、线程创建与启动 线程创建主要有二种方式:- (id)init; // designated initializer - (id)initWithTarget:(id)target selector:(SEL)selector object:(id)argument; 当然,还有一种比较特殊,就是使用所谓的convenient method,这个方法可以直接生成一个线程并启动它,而且无需为线程的清理负责。这个方法的接口是: + (void)detachNewThreadSelector:(SEL)aSelector toTarget:(id)aTarget withObject:(id)anArgument前两种方法创建后,需要手机启动,启动的方法是: - (void)start;二、线程的同步与锁 import <UIKit/UIKit.h> @interface SellTicketsAppDelegate : NSObject <UIApplicationDelegate> { int tickets; int count; NSThread* ticketsThreadone; NSThread* ticketsThreadtwo; NSCondition* ticketsCondition; UIWindow *window; } @property (nonatomic, retain) IBOutlet UIWindow *window; @end SellTicketsAppDelegate.m 文件 // SellTicketsAppDelegate.mimport "SellTicketsAppDelegate.h" @implementation SellTicketsAppDelegate @synthesize window; - (void)applicationDidFinishLaunching:(UIApplication *)application { tickets = 100; count = 0; // 锁对象 ticketCondition = [[NSCondition alloc init; ticketsThreadone = [[NSThread alloc initWithTarget:self selector:@selector(run) object:nil; [ticketsThreadone setName:@"Thread-1"; [ticketsThreadone start; ticketsThreadtwo = [[NSThread alloc initWithTarget:self selector:@selector(run) object:nil; [ticketsThreadtwo setName:@"Thread-2"; [ticketsThreadtwo start; //[NSThread detachNewThreadSelectorselector(run) toTarget:self withObject:nil]; // Override point for customization after application launch [window makeKeyAndVisible; } - (void)run{ while (TRUE) { // 上锁 [ticketsCondition lock; if(tickets > 0){ [NSThread sleepForTimeInterval:0.5; count = 100 - tickets; NSLog(@"当前票数是:%d,售出:%d,线程名:%@",tickets,count,[[NSThread currentThread name); tickets--; }else{ break; } [ticketsCondition unlock; } } - (void)dealloc { [ticketsThreadone release; [ticketsThreadtwo release; [ticketsCondition release; [window release; [super dealloc; } @end 三、线程的交互 由于在本过程中,可能需要释放一些资源,则需要使用NSAutoreleasePool来进行管理,如: - (void)startTheBackgroundJob {NSAutoreleasePool *pool = [[NSAutoreleasePool alloc init; // to do something in your thread job ... [self performSelectorOnMainThread:@selector(makeMyProgressBarMoving) withObject:nil waitUntilDone:NO; [pool release; } |
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