【转】iphone开发之多线程NSThread和NSInvocationOperation
2013-03-17 21:26 maying_07 阅读(144) 评论(0) 编辑 收藏 举报原文地址:http://www.cnblogs.com/lm3515/archive/2011/04/13/2015304.html
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:
1 @implementation MyCustomClass 2 - (void)launchTaskWithData:(id)data 3 { 4 //创建一个NSInvocationOperation对象,并初始化到方法 5 //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) 6 //在这里,object后的值是想传递给前面方法的数据 7 NSInvocationOperation* theOp = [[NSInvocationOperation alloc] initWithTarget:self 8 selector:@selector(myTaskMethod:) object:data]; 9 10 // 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) 11 // 更多的时候是由我们自己建立“操作”队列 12 [[MyAppDelegate sharedOperationQueue] addOperation:theOp]; 13 } 14 15 // 这个是真正运行在另外一个线程的“方法” 16 - (void)myTaskMethod:(id)data 17 { 18 // Perform the task. 19 } 20 21 @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:
1 @interface MyViewController : UIViewController { 2 3 NSOperationQueue *operationQueue; 4 //在头文件中声明该队列 5 } 6 @end 7 8 @implementation MyViewController 9 10 - (id)init 11 { 12 self = [super init]; 13 if (self) { 14 operationQueue = [[NSOperationQueue alloc] init]; //初始化操作队列 15 [operationQueue setMaxConcurrentOperationCount:1]; 16 //在这里限定了该队列只同时运行一个线程 17 //这个队列已经可以使用了 18 } 19 return self; 20 } 21 22 - (void)dealloc 23 { 24 [operationQueue release]; 25 //正如Alan经常说的,我们是程序的好公民,需要释放内存! 26 [super dealloc]; 27 } 28 29 @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)sender
8 {
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。
1 #import <UIKit/UIKit.h> 2 @interface SellTicketsAppDelegate : NSObject <UIApplicationDelegate> { 3 int tickets; 4 int count; 5 NSThread* ticketsThreadone; 6 NSThread* ticketsThreadtwo; 7 NSCondition* ticketsCondition; 8 UIWindow *window; 9 } 10 11 @property (nonatomic, retain) IBOutlet UIWindow *window; 12 @end
然后在实现中添加如下代码:
1 // SellTicketsAppDelegate.m 2 // SellTickets 3 // 4 // Created by sun dfsun2009 on 09-11-10. 5 // Copyright __MyCompanyName__ 2009. All rights reserved. 6 // 7 #import "SellTicketsAppDelegate.h" 8 @implementation SellTicketsAppDelegate 9 @synthesize window; 10 - (void)applicationDidFinishLaunching:(UIApplication *)application { 11 tickets = 100; 12 count = 0; 13 // 锁对象 14 ticketCondition = [[NSCondition alloc] init]; 15 ticketsThreadone = [[NSThread alloc] initWithTarget:self selector:@selector(run) object:nil]; 16 [ticketsThreadone setName:@"Thread-1"]; 17 [ticketsThreadone start]; 18 ticketsThreadtwo = [[NSThread alloc] initWithTarget:self selector:@selector(run) object:nil]; 19 [ticketsThreadtwo setName:@"Thread-2"]; 20 [ticketsThreadtwo start]; 21 //[NSThread detachNewThreadSelector:@selector(run) toTarget:self withObject:nil]; 22 // Override point for customization after application launch 23 [window makeKeyAndVisible]; 24 } 25 - (void)run{ 26 while (TRUE) { 27 // 上锁 28 [ticketsCondition lock]; 29 if(tickets > 0) 30 { 31 [NSThread sleepForTimeInterval:0.5]; 32 count = 100 - tickets; 33 NSLog(@"当前票数是:%d,售出:%d,线程名:%@",tickets,count,[[NSThread currentThread] name]); 34 tickets--; 35 }else 36 { 37 break; 38 } 39 [ticketsCondition unlock]; 40 } 41 } 42 - (void)dealloc { 43 [ticketsThreadone release]; 44 [ticketsThreadtwo release]; 45 [ticketsCondition release]; 46 [window release]; 47 [super dealloc]; 48 } 49 @end
1 // 定义 2 #import <UIKit/UIKit.h> 3 4 @interface ThreadSyncSampleViewController : UIViewController { 5 int _threadCount; 6 NSCondition *_myCondition; 7 } 8 9 @end
1 //实现文件如下: 2 3 #import "ThreadSyncSampleViewController.h" 4 5 @implementation ThreadSyncSampleViewController 6 7 /* 8 // The designated initializer. Override to perform setup that is required before the view is loaded. 9 - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { 10 if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { 11 // Custom initialization 12 } 13 return self; 14 } 15 */ 16 17 /* 18 // Implement loadView to create a view hierarchy programmatically, without using a nib. 19 - (void)loadView { 20 } 21 */ 22 23 // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. 24 - (void)viewDidLoad { 25 [super viewDidLoad]; 26 // 27 //_myCondition = nil; 28 // 29 _myCondition = [[NSCondition alloc] init]; 30 // 31 NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:30 32 target:self 33 selector:@selector(threadTester) 34 userInfo:nil 35 repeats:YES]; 36 [timer fire]; 37 38 } 39 40 41 - (void)threadTester{ 42 [_myCondition lock]; 43 44 _threadCount = -2; 45 //如果有n个要等待的thread,这里置成 -n 46 [_myCondition unlock]; 47 // 48 NSLog(@""); 49 NSLog(@"------------------------------------------------------------------------------"); 50 [NSThread detachNewThreadSelector:@selector(threadOne) toTarget:self withObject:nil]; 51 [NSThread detachNewThreadSelector:@selector(threadTwo) toTarget:self withObject:nil]; 52 [NSThread detachNewThreadSelector:@selector(threadThree) toTarget:self withObject:nil]; 53 return; 54 } 55 56 - (void)threadOne{ 57 NSLog(@"@@@ In thread 111111 start."); 58 [_myCondition lock]; 59 60 int n = rand()%5 + 1; 61 NSLog(@"@@@ Thread 111111 Will sleep %d seconds ,now _threadCount is : %d",n,_threadCount); 62 sleep(n); 63 //[NSThread sleepForTimeInterval:n]; 64 _threadCount ++ ; 65 NSLog(@"@@@ Thread 111111 has sleep %d seconds ,now _threadCount is : %d",n,_threadCount); 66 [_myCondition signal]; 67 NSLog(@"@@@ Thread 1111111 has signaled ,now _threadCount is : %d",_threadCount); 68 [_myCondition unlock]; 69 NSLog(@"@@@ In thread one complete."); 70 [NSThread exit]; 71 return; 72 } 73 74 - (void)threadTwo{ 75 NSLog(@"### In thread 2222222 start."); 76 [_myCondition lock]; 77 78 int n = rand()%5 + 1; 79 NSLog(@"### Thread 2222222 Will sleep %d seconds ,now _threadCount is : %d",n,_threadCount); 80 sleep(n); 81 // [NSThread sleepForTimeInterval:n]; 82 _threadCount ++ ; 83 NSLog(@"### Thread 2222222 has sleep %d seconds ,now _threadCount is : %d",n,_threadCount); 84 [_myCondition signal]; 85 NSLog(@"### Thread 2222222 has signaled ,now _threadCount is : %d",_threadCount); 86 [_myCondition unlock]; 87 //_threadCount ++ ; 88 NSLog(@"### In thread 2222222 complete."); 89 [NSThread exit]; 90 return; 91 } 92 93 - (void)threadThree{ 94 NSLog(@"<<< In thread 333333 start."); 95 [_myCondition lock]; 96 while (_threadCount < 0) { 97 [_myCondition wait]; 98 } 99 NSLog(@"<<< In thread 333333 ,_threadCount now is %d ,will start work.",_threadCount); 100 [_myCondition unlock]; 101 NSLog(@"<<< In thread 333333 complete."); 102 [NSThread exit]; 103 return; 104 } 105 106 /* 107 // Override to allow orientations other than the default portrait orientation. 108 - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { 109 // Return YES for supported orientations 110 return (interfaceOrientation == UIInterfaceOrientationPortrait); 111 } 112 */ 113 114 - (void)didReceiveMemoryWarning { 115 // Releases the view if it doesn't have a superview. 116 [super didReceiveMemoryWarning]; 117 118 // Release any cached data, images, etc that aren't in use. 119 } 120 121 - (void)viewDidUnload { 122 // Release any retained subviews of the main view. 123 // e.g. self.myOutlet = nil; 124 } 125 126 127 - (void)dealloc { 128 [_myCondition release]; 129 [super dealloc]; 130 } 131 132 @end