KCMainViewController.m

//
//  线程控制
//  MultiThread
//
//  Created by Kenshin Cui on 14-3-22.
//  Copyright (c) 2014年 Kenshin Cui. All rights reserved.
//

#import "KCMainViewController.h"
#import "KCImageData.h"
#define ROW_COUNT 5
#define COLUMN_COUNT 3
#define ROW_HEIGHT 100
#define ROW_WIDTH ROW_HEIGHT
#define CELL_SPACING 10
#define IMAGE_COUNT 9

@interface KCMainViewController (){
    NSMutableArray *_imageViews;
    NSCondition *_condition;
}

@end

@implementation KCMainViewController

#pragma mark - 事件
- (void)viewDidLoad {
    [super viewDidLoad];

    [self layoutUI];
}

#pragma mark - 内部私有方法
#pragma mark 界面布局
-(void)layoutUI{
    //创建多个图片空间用于显示图片
    _imageViews=[NSMutableArray array];
    for (int r=0; r<ROW_COUNT; r++) {
        for (int c=0; c<COLUMN_COUNT; c++) {
            UIImageView *imageView=[[UIImageView alloc]initWithFrame:CGRectMake(c*ROW_WIDTH+(c*CELL_SPACING), r*ROW_HEIGHT+(r*CELL_SPACING                           ), ROW_WIDTH, ROW_HEIGHT)];
            imageView.contentMode=UIViewContentModeScaleAspectFit;
            [self.view addSubview:imageView];
            [_imageViews addObject:imageView];
            
        }
    }
    
    UIButton *btnLoad=[UIButton buttonWithType:UIButtonTypeRoundedRect];
    btnLoad.frame=CGRectMake(50, 500, 100, 25);
    [btnLoad setTitle:@"加载图片" forState:UIControlStateNormal];
    [btnLoad addTarget:self action:@selector(loadImageWithMultiThread) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btnLoad];
    
    UIButton *btnCreate=[UIButton buttonWithType:UIButtonTypeRoundedRect];
    btnCreate.frame=CGRectMake(160, 500, 100, 25);
    [btnCreate setTitle:@"创建图片" forState:UIControlStateNormal];
    [btnCreate addTarget:self action:@selector(createImageWithMultiThread) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btnCreate];
    
    //创建图片链接
    _imageNames=[NSMutableArray array];
    
    //初始化锁对象
    _condition=[[NSCondition alloc]init];
    
    _currentIndex=0;
    
}


#pragma mark 创建图片
-(void)createImageName{
    [_condition lock];
    //如果当前已经有图片了则不再创建，线程处于等待状态
    if (_imageNames.count>0) {
        NSLog(@"createImageName wait, current:%i",_currentIndex);
        [_condition wait];
    }else{
        NSLog(@"createImageName work, current:%i",_currentIndex);
        //生产者，每次生产1张图片
        [_imageNames addObject:[NSString stringWithFormat:@"http://images.cnblogs.com/cnblogs_com/kenshincui/613474/o_%i.jpg",_currentIndex++]];
        
        //创建完图片则发出信号唤醒其他等待线程
        [_condition signal];
    }
    [_condition unlock];
    
    [dispatch_get_main_queue() addObserver:<#(NSObject *)#> forKeyPath:<#(NSString *)#> options:<#(NSKeyValueObservingOptions)#> context:<#(void *)#>]
}

#pragma mark 加载图片并将图片显示到界面
-(void)loadAnUpdateImageWithIndex:(int )index{
    //请求数据
    NSData *data= [self requestData:index];
    //更新UI界面,此处调用了GCD主线程队列的方法
    dispatch_queue_t mainQueue= dispatch_get_main_queue();
    dispatch_sync(mainQueue, ^{
        UIImage *image=[UIImage imageWithData:data];
        UIImageView *imageView= _imageViews[index];
        imageView.image=image;
    });
}

#pragma mark 请求图片数据
-(NSData *)requestData:(int )index{
    NSData *data;
    NSString *name;
    name=[_imageNames lastObject];
    [_imageNames removeObject:name];
    if(name){
        NSURL *url=[NSURL URLWithString:name];
        data=[NSData dataWithContentsOfURL:url];
    }
    return data;
}

#pragma mark 加载图片
-(void)loadImage:(NSNumber *)index{
    int i=(int)[index integerValue];
    //加锁
    [_condition lock];
    //如果当前有图片资源则加载，否则等待
    if (_imageNames.count>0) {
        NSLog(@"loadImage work,index is %i",i);
        [self loadAnUpdateImageWithIndex:i];
        [_condition broadcast];
    }else{
        NSLog(@"loadImage wait,index is %i",i);
        NSLog(@"%@",[NSThread currentThread]);
        //线程等待
        [_condition wait];
        NSLog(@"loadImage resore,index is %i",i);
        //一旦创建完图片立即加载
        [self loadAnUpdateImageWithIndex:i];
    }
    //解锁
    [_condition unlock];
}


#pragma mark - UI调用方法
#pragma mark 异步创建一张图片链接
-(void)createImageWithMultiThread{
    dispatch_queue_t globalQueue=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    //创建图片链接
    dispatch_async(globalQueue, ^{
        [self createImageName];
    });
}

#pragma mark 多线程下载图片
-(void)loadImageWithMultiThread{
    int count=ROW_COUNT*COLUMN_COUNT;
    dispatch_queue_t globalQueue=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

    for (int i=0; i<count; ++i) {
        //加载图片
        dispatch_async(globalQueue, ^{
            [self loadImage:[NSNumber numberWithInt:i]];
        });
    }
}
@end