// DYFViewController.m// 623-08-队列组//// Created by dyf on 14-6-23.// Copyright (c) 2014年 ___FULLUSERNAME___. All rights reserved.//#import "DYFViewController.h"@interface DYFViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *iconV1;
@property (weak, nonatomic) IBOutlet UIImageView *iconV2;
@property (weak, nonatomic) IBOutlet UIImageView *bigIconV;
@end@implementation DYFViewController
- (void)viewDidLoad
{ [super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}- (void)didReceiveMemoryWarning
{ [super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{ NSLog(@"%@", [NSThread currentThread]);
dispatch_group_t group = dispatch_group_create();
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
__block UIImage *icon1 = nil;
dispatch_group_async(group, queue, ^{
NSLog(@"%@", [NSThread currentThread]);
//
});
__block UIImage *icon2 = nil;
dispatch_group_async(group, queue, ^{
NSLog(@"%@", [NSThread currentThread]);
//
icon2 = [self imageWithURL:@"http://news.baidu.com/z/resource/r/image/2014-06-22/b2a9cfc88b7a56cfa59b8d09208fa1fb.jpg"];
});
dispatch_group_notify(group, dispatch_get_main_queue(), ^{
NSLog(@"%@", [NSThread currentThread]);
//
self.iconV1.image = icon1;
self.iconV2.image = icon2;
UIGraphicsBeginImageContextWithOptions(CGSizeMake(200, 100), NO, 0);
[icon1 drawInRect:CGRectMake(0, 0, 100, 100)];
[icon2 drawInRect:CGRectMake(100, 0, 100, 100)];
self.bigIconV.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
});
}- (UIImage *)imageWithURL:(NSString *)iconPath
{ NSLog(@"%@", [NSThread currentThread]);
NSURL *url = [NSURL URLWithString:iconPath];
NSData *data = [NSData dataWithContentsOfURL:url];
return [UIImage imageWithData:data];
}@end小结：
------------队列组------
1.有这么一种需求
·首先：分别异步执行2个耗时的操作
·其次：等2各异步操作都执行完毕后，再回到主线程执行操作
2.若想要快速高效的实现上述需求，可以考虑用队列组