iOS-队列组

//
//  HMViewController.m
//  03-队列组（了解）
//
//  Created by apple on 14-9-16.
//  Copyright (c) 2014年 heima. All rights reserved.
//

#import "HMViewController.h"

// 1.分别下载2张图片：大图片、LOGO
// 2.合并2张图片
// 3.显示到一个imageView身上

@interface HMViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@property (nonatomic, strong) UIImage *image1;
@property (nonatomic, strong) UIImage *image2;
@end

@implementation HMViewController

- (void)viewDidLoad
{
[super viewDidLoad];

}

// 2D绘图  Quartz2D
// 合并图片 -- 水印

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
// 1.队列组
dispatch_group_t group = dispatch_group_create();
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

// 2.下载图片1
__block UIImage *image1 = nil;
dispatch_group_async(group, queue, ^{
NSURL *url1 = [NSURL URLWithString:@"http://g.hiphotos.baidu.com/image/pic/item/f2deb48f8c5494ee460de6182ff5e0fe99257e80.jpg"];
NSData *data1 = [NSData dataWithContentsOfURL:url1];
image1 = [UIImage imageWithData:data1];
});

// 3.下载图片2
__block UIImage *image2 = nil;
dispatch_group_async(group, queue, ^{
NSURL *url2 = [NSURL URLWithString:@"http://su.bdimg.com/static/superplus/img/logo_white_ee663702.png"];
NSData *data2 = [NSData dataWithContentsOfURL:url2];
image2 = [UIImage imageWithData:data2];
});

// 4.合并图片 (保证执行完组里面的所有任务之后，再执行notify函数里面的block)
dispatch_group_notify(group, queue, ^{
// 开启一个位图上下文
UIGraphicsBeginImageContextWithOptions(image1.size, NO, 0.0);

// 绘制第1张图片
CGFloat image1W = image1.size.width;
CGFloat image1H = image1.size.height;
[image1 drawInRect:CGRectMake(0, 0, image1W, image1H)];

// 绘制第2张图片
CGFloat image2W = image2.size.width * 0.5;
CGFloat image2H = image2.size.height * 0.5;
CGFloat image2Y = image1H - image2H;
[image2 drawInRect:CGRectMake(0, image2Y, image2W, image2H)];

// 得到上下文中的图片
UIImage *fullImage = UIGraphicsGetImageFromCurrentImageContext();

// 结束上下文
UIGraphicsEndImageContext();

// 5.回到主线程显示图片
dispatch_async(dispatch_get_main_queue(), ^{
self.imageView.image = fullImage;
});
});
}

- (void)test2
{
// 异步下载
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// 1.下载第1张
NSURL *url1 = [NSURL URLWithString:@"http://g.hiphotos.baidu.com/image/pic/item/f2deb48f8c5494ee460de6182ff5e0fe99257e80.jpg"];
NSData *data1 = [NSData dataWithContentsOfURL:url1];
self.image1 = [UIImage imageWithData:data1];

[self bindImages];
});
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// 2.下载第2张
NSURL *url2 = [NSURL URLWithString:@"http://su.bdimg.com/static/superplus/img/logo_white_ee663702.png"];
NSData *data2 = [NSData dataWithContentsOfURL:url2];
self.image2 = [UIImage imageWithData:data2];

[self bindImages];
});
}

- (void)bindImages
{
if (self.image1 == nil || self.image2 == nil) return;

// 3.合并图片
// 开启一个位图上下文
UIGraphicsBeginImageContextWithOptions(self.image1.size, NO, 0.0);

// 绘制第1张图片
CGFloat image1W = self.image1.size.width;
CGFloat image1H = self.image1.size.height;
[self.image1 drawInRect:CGRectMake(0, 0, image1W, image1H)];

// 绘制第2张图片
CGFloat image2W = self.image2.size.width * 0.5;
CGFloat image2H = self.image2.size.height * 0.5;
CGFloat image2Y = image1H - image2H;
[self.image2 drawInRect:CGRectMake(0, image2Y, image2W, image2H)];

// 得到上下文中的图片
UIImage *fullImage = UIGraphicsGetImageFromCurrentImageContext();

// 结束上下文
UIGraphicsEndImageContext();

// 4.回到主线程显示图片
dispatch_async(dispatch_get_main_queue(), ^{
self.imageView.image = fullImage;
});
}

- (void)test1
{
// 异步下载
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// 1.下载第1张
NSURL *url1 = [NSURL URLWithString:@"http://g.hiphotos.baidu.com/image/pic/item/f2deb48f8c5494ee460de6182ff5e0fe99257e80.jpg"];
NSData *data1 = [NSData dataWithContentsOfURL:url1];
UIImage *image1 = [UIImage imageWithData:data1];

// 2.下载第2张
NSURL *url2 = [NSURL URLWithString:@"http://su.bdimg.com/static/superplus/img/logo_white_ee663702.png"];
NSData *data2 = [NSData dataWithContentsOfURL:url2];
UIImage *image2 = [UIImage imageWithData:data2];

// 3.合并图片
// 开启一个位图上下文
UIGraphicsBeginImageContextWithOptions(image1.size, NO, 0.0);

// 绘制第1张图片
CGFloat image1W = image1.size.width;
CGFloat image1H = image1.size.height;
[image1 drawInRect:CGRectMake(0, 0, image1W, image1H)];

// 绘制第2张图片
CGFloat image2W = image2.size.width * 0.5;
CGFloat image2H = image2.size.height * 0.5;
CGFloat image2Y = image1H - image2H;
[image2 drawInRect:CGRectMake(0, image2Y, image2W, image2H)];

// 得到上下文中的图片
UIImage *fullImage = UIGraphicsGetImageFromCurrentImageContext();

// 结束上下文
UIGraphicsEndImageContext();

// 4.回到主线程显示图片
dispatch_async(dispatch_get_main_queue(), ^{
self.imageView.image = fullImage;
});
});
}

@end