以下是开发初期收集整理的一点资料 多线程之NSInvocationOperation多线程编程是防止主线程堵塞，增加运行效率等等的最佳方法。而原始的多线程方法存在很多的毛病，包括线程锁死等。在Cocoa中，Apple提供了NSOperation这个类，提供了一个优秀的多线程编程方法。本次介绍NSOperation的子集，简易方法的NSInvocationOperation：@implementation MyCustomClass - (void)launchTaskWithData:(id)data{    //创建一个NSInvocationOperation对象，并初始化到方法    //在这里，selector参数后的值是你想在另外一个线程中运行的方法（函数，Method）    //在这里，object后的值是想传递给前面方法的数据    NSInvocationOperation* theOp = [[NSInvocationOperation alloc] initWithTarget:self                    selector:@selector(myTaskMethod:) object:data];     // 下面将我们建立的操作“Operation”加入到本地程序的共享队列中（加入后方法就会立刻被执行）    // 更多的时候是由我们自己建立“操作”队列    [[MyAppDelegate sharedOperationQueue] addOperation:theOp];} // 这个是真正运行在另外一个线程的“方法”- (void)myTaskMethod:(id)data{    // Perform the task.} @end一个NSOperationQueue 操作队列，就相当于一个线程管理器，而非一个线程。因为你可以设置这个线程管理器内可以并行运行的的线程数量等等。下面是建立并初始化一个操作队列：@interface MyViewController : UIViewController {     NSOperationQueue *operationQueue;    //在头文件中声明该队列}@end @implementation MyViewController - (id)init {    self = [super init];    if (self) {        operationQueue = [[NSOperationQueue alloc] init]; //初始化操作队列        [operationQueue setMaxConcurrentOperationCount:1];        //在这里限定了该队列只同时运行一个线程        //这个队列已经可以使用了    }    return self;} - (void)dealloc{    [operationQueue release];    //正如Alan经常说的，我们是程序的好公民，需要释放内存！    [super dealloc];} @end简单介绍之后，其实可以发现这种方法是非常简单的。很多的时候我们使用多线程仅仅是为了防止主线程堵塞，而NSInvocationOperation就是最简单的多线程编程，在iPhone编程中是经常被用到的。///1 在主线程里加入一个loading画面……2 {3 [window addSubview:view_loading];4 [NSThread detachNewThreadSelector:@selector(init_backup:) toTarget:self withObject:nil];5 }可以通过performSelectorOhMainThread更新UI元素，比如设置进度条等等。最后消除loading画面，载入主View。7 - (void)init_backup:(id)sender8 {9 NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];10 11 // ...12 int i = status;13 [self performSelectorOnMainThread:@selector(show_loading:) withObject:[NSNumber numberWithInt:i] waitUntil Done:NO];14 15 [view_loading removeFromSuperview];16 [window addSubview:tabcontroller_main.view];17 [pool release];18 } ///利用iphone的多线程实现和线程同步从接口的定义中可以知道，NSThread和大多数iphone的接口对象一样，有两种方式可以初始化：一种使用initWithTarget :(id)target selector:(SEL)selector object:(id)argument，但需要负责在对象的retain count为0时调用对象的release方法清理对象。另一种则使用所谓的convenient method,这个方便接口就是detachNewThreadSelector，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。#import 
     
      @interface SellTicketsAppDelegate : NSObject 
      
        {    int tickets;    int count;    NSThread* ticketsThreadone;    NSThread* ticketsThreadtwo;    NSCondition* ticketsCondition;    UIWindow *window;}@property (nonatomic, retain) IBOutlet UIWindow *window;@end 然后在实现中添加如下代码：//  SellTicketsAppDelegate.m//  SellTickets////  Created by sun dfsun2009 on 09-11-10.//  Copyright __MyCompanyName__ 2009. All rights reserved.//#import "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 detachNewThreadSelector:@selector(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-------------------------------------------------------------------------------------// 定义#import 
       
        @interface ThreadSyncSampleViewController : UIViewController { int _threadCount; NSCondition *_myCondition;}@end//实现文件如下:#import "ThreadSyncSampleViewController.h"@implementation ThreadSyncSampleViewController /*// The designated initializer. Override to perform setup that is required before the view is loaded.- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {    if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {        // Custom initialization    }    return self;}*//*// Implement loadView to create a view hierarchy programmatically, without using a nib.- (void)loadView {}*/ // Implement viewDidLoad to do additional setup after loading the view, typically from a nib.- (void)viewDidLoad {    [super viewDidLoad]; // //_myCondition = nil; // _myCondition = [[NSCondition alloc] init]; // NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:30              target:self              selector:@selector(threadTester)              userInfo:nil             repeats:YES]; [timer fire]; }- (void)threadTester{ [_myCondition lock];  _threadCount = -2; //如果有n个要等待的thread，这里置成 -n [_myCondition unlock]; // NSLog(@""); NSLog(@"------------------------------------------------------------------------------"); [NSThread detachNewThreadSelector:@selector(threadOne) toTarget:self withObject:nil]; [NSThread detachNewThreadSelector:@selector(threadTwo) toTarget:self withObject:nil]; [NSThread detachNewThreadSelector:@selector(threadThree) toTarget:self withObject:nil]; return;}- (void)threadOne{ NSLog(@"@@@ In thread 111111 start."); [_myCondition lock];  int n = rand()%5 + 1; NSLog(@"@@@ Thread 111111 Will sleep %d seconds ,now _threadCount is : %d",n,_threadCount); sleep(n); //[NSThread sleepForTimeInterval:n]; _threadCount ++ ; NSLog(@"@@@ Thread 111111 has sleep %d seconds ,now _threadCount is : %d",n,_threadCount); [_myCondition signal]; NSLog(@"@@@ Thread 1111111 has signaled ,now _threadCount is : %d",_threadCount); [_myCondition unlock]; NSLog(@"@@@ In thread one complete."); [NSThread exit]; return;}- (void)threadTwo{ NSLog(@"### In thread 2222222 start."); [_myCondition lock];  int n = rand()%5 + 1; NSLog(@"### Thread 2222222 Will sleep %d seconds ,now _threadCount is : %d",n,_threadCount); sleep(n); //   [NSThread sleepForTimeInterval:n]; _threadCount ++ ; NSLog(@"### Thread 2222222 has sleep %d seconds ,now _threadCount is : %d",n,_threadCount); [_myCondition signal]; NSLog(@"### Thread 2222222 has signaled ,now _threadCount is : %d",_threadCount); [_myCondition unlock]; //_threadCount ++ ; NSLog(@"### In thread 2222222 complete."); [NSThread exit]; return;}- (void)threadThree{ NSLog(@"<<< In thread 333333 start."); [_myCondition lock]; while (_threadCount < 0) {  [_myCondition wait]; } NSLog(@"<<< In thread 333333 ,_threadCount now is %d ,will start work.",_threadCount); [_myCondition unlock]; NSLog(@"<<< In thread 333333 complete."); [NSThread exit]; return;}/*// Override to allow orientations other than the default portrait orientation.- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {    // Return YES for supported orientations    return (interfaceOrientation == UIInterfaceOrientationPortrait);}*/- (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview.    [super didReceiveMemoryWarning];  // Release any cached data, images, etc that aren't in use.}- (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil;}- (void)dealloc { [_myCondition release];    [super dealloc];}@end