iOS多线程开发之GCD 用法入门

 1 //
 2 //  MainView.m
 3 //  GCDDemo
 4 //
 5 //  Created by pigpigdaddy on 14-9-29.
 6 //  Copyright (c) 2014年 pigpigdaddy. All rights reserved.
 7 //
 8 
 9 #import "MainView.h"
10 
11 #define ROW_COUNT 5
12 #define COLUMN_COUNT 3
13 #define IMAGEVIEW_BASE_TAG 100
14 
15 @interface MainView()
16 
17 @property (nonatomic, strong)NSMutableArray *dataArray;
18 @property (nonatomic, strong)UIScrollView *scrollView;
19 
20 @end
21 
22 @implementation MainView
23 
24 - (id)initWithFrame:(CGRect)frame
25 {
26     self = [super initWithFrame:frame];
27     if (self) {
28         // Initialization code
29         [self initData];
30         [self initView];
31     }
32     return self;
33 }
34 
35 - (void)initData
36 {
37     // 存储图片地址的数组
38     self.dataArray = [[NSMutableArray alloc] init];
39     for (int i = 0; i<ROW_COUNT*COLUMN_COUNT; i++) {
40         [self.dataArray addObject:[NSString stringWithFormat:@"http://images.cnblogs.com/cnblogs_com/pigpigDD/616506/o_%d.png", i+1]];
41     }
42 }
43 
44 - (void)initView
45 {
46     // 创建scrollView
47     self.scrollView = [[UIScrollView alloc] initWithFrame:self.bounds];
48     [self addSubview:self.scrollView];
49     
50     // 创建用于显示的UIImageView
51     for (int i = 0; i<ROW_COUNT; i++) {
52         for (int j = 0; j<COLUMN_COUNT; j++) {
53             UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(100*(j%COLUMN_COUNT)+5, 110*(i%ROW_COUNT)+5, 100, 110)];
54             imageView.tag = IMAGEVIEW_BASE_TAG+j+i*3;
55             [self.scrollView addSubview:imageView];
56         }
57     }
58     self.scrollView.contentSize = CGSizeMake(320, 575);
59     
60     // 开始加载的按钮
61     UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
62     button.backgroundColor = [UIColor lightGrayColor];
63     button.frame = CGRectMake(100, self.bounds.size.height-50,80, 30);
64     [button setTitle:@"开始加载" forState:UIControlStateNormal];
65     [button addTarget:self action:@selector(loadImage) forControlEvents:UIControlEventTouchUpInside];
66     [self addSubview:button];
67 }
68 
69 - (void)downImage:(int)index{
70     // 获取图片
71     NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"%@", [self.dataArray objectAtIndex:index]]];
72     NSData *data = [NSData dataWithContentsOfURL:url];
73     
74     UIImage *image = [UIImage imageWithData:data];
75     
76     // 获取主线程队列
77     dispatch_queue_t mainQueue = dispatch_get_main_queue();
78     // 在主线程中更新下载好的图片
79     dispatch_async(mainQueue, ^{
80         UIImageView *imageView = (UIImageView *)[self viewWithTag:IMAGEVIEW_BASE_TAG + index];
81         imageView.image = image;
82     });
83 }
84 
85 
86 - (void)loadImage
87 {
88     // 创建一个串行队列
89     dispatch_queue_t serialQueue = dispatch_queue_create("com.dispatch.serialQueue", DISPATCH_QUEUE_SERIAL);
90     for (int i = 0; i<ROW_COUNT*COLUMN_COUNT; i++) {
91         dispatch_async(serialQueue, ^{
92             [self downImage:i];
93         });
94     }
95 }
96 
97 @end

 1 -(void)loadImage{
 2     int count=ROW_COUNT*COLUMN_COUNT;
 3     
 4     // 使用全局并发队列
 5     //dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
 6     
 7     // 使用自己创建的并发队列
 8     dispatch_queue_t concurrentQueue = dispatch_queue_create("com.dispatch.concurrentQueue", DISPATCH_QUEUE_CONCURRENT);
 9     //创建多个线程用于填充图片
10     for (int i=0; i<count; ++i) {
11         //异步执行队列任务
12         dispatch_async(concurrentQueue, ^{
13             [self downImage:i];
14         });
15     }
16 }