IOS开发/iphone开发多线程

有时候可能有很多功能要同时实现，例如每隔多长时间就会检测程序网络连接，又或者有时候需要从服务器下载一个不小的文件，如果用单线程几乎是不可想的事情，程序将会卡的无法使用，用到多线程和不用多线程，给用户的体验天壤之别，所以多线程是一个ios开发人员必须学会的一个知识点。

多线程，听得有点高深，其实很简单。在iphone中，多线程可以这么理解，除主线程外还有其他线程，主线程和其他线程的区别是最重要的，最简单的理解方法就是主线程会改变界面，其他线程不会改变，主线程可以调用其他线程，

1.声明一个线程又两种方法：1.thread1=[[nsthread alloc]initwithtarget:self selector:@selector(tt1) object:nil];这种方法必须启动 [thread1 start];

                                  2.[nsthread detachnewthreadselector:@selector(tt1) totarget:self withobject:nil];这种方法不需要声明nsthread对象，也不需要启动，默认执行到这句就直接运行了

2.当程序在后台执行时，可能有时候需要调用另外的方法，这个方法名是［self performselectorinbackground:@selector(threadmethod) withobject:nil］

3.设置线程优先级-(void)setthreadpriority:(double)priority;线程优先级是从0.0到1.0，1.0是最高优先级。系统默认的优先级是0.5

4.线程休眠：+(void)sleepfortimeinterval:(nstimeinterval)time;time参数为休眠时间。

5.线程的交互：线程的运行过程中，可能需要与其他线程进行通信，如在主线程中修改界面等等，可以使用如下接口：-(void)performselectoronmainthread:(sel)selectoe   withobject:(id)arg  waituntildone:(bool)wait;

6.线程的同步和线程琐，可以了解下

7.线程池，可以了解下

用多线程实现一个简单的程

#import <uikit/uikit.h>

@interface toolbar_1viewcontroller : uiviewcontroller {

    uilabel * l1;

    uilabel * l2;

    uilabel * l3;

    uilabel * l4;

    uilabel * l5;

    uibutton *b1;

    uibutton *b2;

    uibutton *b3;

    uibutton *b4;

    uibutton *b5;

    nsthread *thread1;

    nsthread *thread2;

    nsthread *thread3;

    nsthread *thread4;

    bool button1;

    bool button2;

    bool button3;

    bool button4;

    bool button5;

    int i1;

    int i2;

    int i3;

    int i4;

    int i5;

    nscondition *lock;

}

@property (nonatomic,retain)iboutlet uilabel *l1;

@property (nonatomic,retain)iboutlet uilabel *l2;

@property (nonatomic,retain)iboutlet uilabel *l3;

@property (nonatomic,retain)iboutlet uilabel *l4;

@property (nonatomic,retain)iboutlet uilabel *l5;

@property (nonatomic,retain)iboutlet uibutton *b1;

@property (nonatomic,retain)iboutlet uibutton *b2;

@property (nonatomic,retain)iboutlet uibutton *b3;

@property (nonatomic,retain)iboutlet uibutton *b4;

@property (nonatomic,retain)iboutlet uibutton *b5;

-(ibaction)b1:(id)sender;

-(ibaction)b2:(id)sender;

-(ibaction)b3:(id)sender;

-(ibaction)b4:(id)sender;

-(ibaction)b5:(id)sender;

-(void)t1;

-(void)tt1;

-(void)t2;

-(void)tt2;

-(void)t3;

-(void)tt3;

-(void)t4;

-(void)tt4;

-(void)changeall;

@end

#import "toolbar_1viewcontroller.h"

@implementation toolbar_1viewcontroller

@synthesize l1;

@synthesize l2;

@synthesize l3;

@synthesize l4;

@synthesize l5;

@synthesize b1;

@synthesize b2;

@synthesize b3;

@synthesize b4;

@synthesize b5;

-(ibaction)b1:(id)sender

{

    thread1=[[nsthread alloc]initwithtarget:self selector:@selector(tt1) object:nil]; 

    button1=!button1;

    if(button1){

        [b1 settitle:@"停止1" forstate:uicontrolstatenormal] ;

        [self changeall];

        [thread1 start];

    }

    else {

        [b1 settitle:@"启动1" forstate:uicontrolstatenormal] ;

        [thread1 cancel];

-(void)changeall

    if (button1&&button2&button3&button4) {

        [b5 settitle:@"停止全部" forstate:uicontrolstatenormal] ;

        button5=yes;

    if (!button1&&!button2&!button3&!button4) {

        [b5 settitle:@"启动全部" forstate:uicontrolstatenormal] ;

        button5=no;

-(void)tt1

    while (button1) {

        [self performselectoronmainthread:@selector(t1) withobject:nil waituntildone:no];

        [nsthread sleepfortimeinterval:1.0];

    }   

-(void)t1

    l1.text=[nsstring stringwithformat:@"%d",++i1];

    [lock lock];

    i5 ++ ;

    [lock unlock];

    l5.text=[nsstring stringwithformat:@"%d",i5];

    [self.view setneedsdisplay];

-(ibaction)b2:(id)sender

    thread2=[[nsthread alloc]initwithtarget:self selector:@selector(tt2) object:nil]; 

    button2=!button2;

    if(button2){

        [b2 settitle:@"停止2" forstate:uicontrolstatenormal] ;

        [thread2 start];

        [b2 settitle:@"启动2" forstate:uicontrolstatenormal] ;

        [thread2 cancel];

-(void)tt2

    while (button2) {

        [self performselectoronmainthread:@selector(t2) withobject:nil waituntildone:no];

-(void)t2

    l2.text=[nsstring stringwithformat:@"%d",++i2];

-(ibaction)b3:(id)sender

    thread3=[[nsthread alloc]initwithtarget:self selector:@selector(tt3) object:nil];

    button3=!button3;

    if(button3){

        [b3 settitle:@"停止3" forstate:uicontrolstatenormal] ;

        [thread3 start];

        [b3 settitle:@"启动3" forstate:uicontrolstatenormal] ;

        [thread3 cancel];

-(void)tt3

    while (button3) {

        [self performselectoronmainthread:@selector(t3) withobject:nil waituntildone:no];

-(void)t3

    l3.text=[nsstring stringwithformat:@"%d",++i3];

-(ibaction)b4:(id)sender

    thread4=[[nsthread alloc]initwithtarget:self selector:@selector(tt4) object:nil];

    button4=!button4;

    if(button4){

        [b4 settitle:@"停止4" forstate:uicontrolstatenormal] ;

        [thread4 start];

        [b4 settitle:@"启动4" forstate:uicontrolstatenormal] ;

        [thread4 cancel];

-(void)tt4

    while (button4) {

        [self performselectoronmainthread:@selector(t4) withobject:nil waituntildone:no];

-(void)t4

    l4.text=[nsstring stringwithformat:@"%d",++i4];

-(ibaction)b5:(id)sender

    if(!button5){

        if (!button1) {

            thread1=[[nsthread alloc]initwithtarget:self selector:@selector(tt1) object:nil]; 

            button1=!button1;

            [b1 settitle:@"停止1" forstate:uicontrolstatenormal] ;

            [thread1 start];

        }

        if (!button2) {

            thread2=[[nsthread alloc]initwithtarget:self selector:@selector(tt2) object:nil]; 

            button2=!button2;

            [b2 settitle:@"停止2" forstate:uicontrolstatenormal] ;

            [thread2 start];

        if (!button3) {

            thread3=[[nsthread alloc]initwithtarget:self selector:@selector(tt3) object:nil]; 

            button3=!button3;

            [b3 settitle:@"停止3" forstate:uicontrolstatenormal] ;

            [thread3 start];

        if (!button4) {

            thread4=[[nsthread alloc]initwithtarget:self selector:@selector(tt4) object:nil]; 

            button4=!button4;

            [b4 settitle:@"停止4" forstate:uicontrolstatenormal] ;

            [thread4 start];

    else{

        if (button1) {

            [b1 settitle:@"启动1" forstate:uicontrolstatenormal] ;

            [thread1 cancel];

        if (button2) {

            [b2 settitle:@"启动2" forstate:uicontrolstatenormal] ;

            [thread2 cancel];

        if (button3) {

            [b3 settitle:@"启动3" forstate:uicontrolstatenormal] ;

            [thread3 cancel];

        if (button4) {

            [b4 settitle:@"启动4" forstate:uicontrolstatenormal] ;

            [thread4 cancel];

        }       

    button5=!button5;

- (void)dealloc

    [l1 release];

    [l2 release];

    [l3 release];

    [l4 release];

    [l5 release];

    [b1 release];

    [b2 release];

    [b3 release];

    [b4 release];

    [b5 release];

    [thread1 release];

    [thread2 release];

    [thread3 release];

    [thread4 release];

    [super dealloc];

- (void)viewdidload

    i1=0;

    button1=false;

    button2=false;

    button3=false;

    button4=false;

    button5=false;

    i5=i2=i3=i4=i1;

    l1.text=[nsstring stringwithformat:@"%d",i1];

    l2.text=[nsstring stringwithformat:@"%d",i2];

    l3.text=[nsstring stringwithformat:@"%d",i3];

    l4.text=[nsstring stringwithformat:@"%d",i4];

xib文件如下