队列组-合并图片-07-08-09-GCD

//
//  ViewController.m
//  07-合并图片
//
//  Created by mac on 16/4/21.
//  Copyright © 2016年 mac. All rights reserved.
//
//    NSURL *url = [NSURL URLWithString:@"http://h.hiphotos.baidu.com/image/pic/item/574e9258d109b3dedb168a8ec8bf6c81810a4cae.jpg"];
//    NSURL *url = [NSURL URLWithString:@"https://ss0.bdstatic.com/5aV1bjqh_Q23odCf/static/superman/img/logo/bd_logo1_31bdc765.png"];

#import "UIImageView+WebCache.h"
#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController {
    
    UIImageView *imageView;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    imageView = [[UIImageView alloc] initWithFrame:self.view.frame];
    imageView.backgroundColor = [UIColor cyanColor];
    
    [self.view addSubview:imageView];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        
        //1. 下载第一张图片
        NSURL *url = [NSURL URLWithString:@"https://ss0.bdstatic.com/5aV1bjqh_Q23odCf/static/superman/img/logo/bd_logo1_31bdc765.png"];
        
        NSData *data = [NSData dataWithContentsOfURL:url];
        UIImage *image = [UIImage imageWithData:data];
        
        //2. 下载第二种图片
        NSURL *url2 = [NSURL URLWithString:@"http://www.jushuo.com/uploads/allimg/151204/5-1512040Z34a50.jpg"];
        
        NSData *data2 = [NSData dataWithContentsOfURL:url2];
        UIImage *image2 = [UIImage imageWithData:data2];
        
        
        //3. 合并 ：
        //1）开启一个位图上下文
        UIGraphicsBeginImageContextWithOptions(image.size, NO, 0.0);
        
        //2) 绘制第一张和第二张图
        [image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)];
        [image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height * 0.5)];
        
        //3) 得到上下文中的图片
        UIImage *fullImage = UIGraphicsGetImageFromCurrentImageContext();
        
        //4) 结束上下文
        UIGraphicsEndImageContext();
        
        
        //4. 主线程中加载UI
        dispatch_async(dispatch_get_main_queue(), ^{
           
            imageView.image = fullImage;
        });

    });
}

@end

//
//  ViewController.m
//  08-队列组-GCD
//
//  Created by mac on 16/4/21.
//  Copyright © 2016年 mac. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController {

    UIImageView *imageView;
    UIImage *image;
    UIImage *image2;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    imageView = [[UIImageView alloc] initWithFrame:self.view.frame];
    imageView.backgroundColor = [UIColor cyanColor];
    
    [self.view addSubview:imageView];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    
    if (image || image2) return;
    
    NSLog(@"hahaha");
    
    [self downloadImage];
}

- (void)downloadImage {
    
        //1. 下载第一张图片
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        
        NSURL *url = [NSURL URLWithString:@"https://ss0.bdstatic.com/5aV1bjqh_Q23odCf/static/superman/img/logo/bd_logo1_31bdc765.png"];
        NSData *data = [NSData dataWithContentsOfURL:url];
        image = [UIImage imageWithData:data];
        
        [self text];
    });
    
       //2. 下载第二张图片
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        
        NSURL *url2 = [NSURL URLWithString:@"http://www.jushuo.com/uploads/allimg/151204/5-1512040Z34a50.jpg"];
        NSData *data2 = [NSData dataWithContentsOfURL:url2];
        image2 = [UIImage imageWithData:data2];
        
        [self text];
    });
}

- (void)text {
    
    if (image == nil || image2 == nil) return;
        
    //3. 合并 ：

    //1）开启一个位图上下文
        UIGraphicsBeginImageContextWithOptions(image.size, NO, 0.0);
        
        //2) 绘制第一张和第二张图
        [image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)];
        [image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height * 0.5)];
        
        //3) 得到上下文中的图片
        UIImage *fullImage = UIGraphicsGetImageFromCurrentImageContext();
        
        //4) 结束上下文
        UIGraphicsEndImageContext();
        
        //4. 主线程中加载UI
        dispatch_async(dispatch_get_main_queue(), ^{
            
            imageView.image = fullImage;
        });
}

@end

//
//  NewViewController.m
//  08-队列组-GCD
//
//  Created by mac on 16/4/21.
//  Copyright © 2016年 mac. All rights reserved.
//

#import "NewViewController.h"

@interface NewViewController ()

@end

@implementation NewViewController {
    
        UIImageView *imageView;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    imageView = [[UIImageView alloc] initWithFrame:self.view.frame];
    imageView.backgroundColor = [UIColor cyanColor];
    
    [self.view addSubview:imageView];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    
    [self downloadImage];
    NSLog(@"downloadImage");
}

/**
 *  队列组（dispatch_group_t ）（dispatch_group_notify）
 */
- (void)downloadImage {
    
    //1. 队列组
    dispatch_group_t group = dispatch_group_create();
    
    //2. 队列
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    
    //3. 下载第一张图片
    __block UIImage *image = nil;
    dispatch_group_async(group, queue, ^{
        
        NSURL *url = [NSURL URLWithString:@"https://ss0.bdstatic.com/5aV1bjqh_Q23odCf/static/superman/img/logo/bd_logo1_31bdc765.png"];
        NSData *data = [NSData dataWithContentsOfURL:url];
        image = [UIImage imageWithData:data];
    });
    
    //4. 下载第二张图片
    __block UIImage *image2 = nil;
    dispatch_group_async(group, queue, ^{
        
        NSURL *url2 = [NSURL URLWithString:@"http://www.jushuo.com/uploads/allimg/151204/5-1512040Z34a50.jpg"];
        NSData *data2 = [NSData dataWithContentsOfURL:url2];
        image2 = [UIImage imageWithData:data2];
    });
    
    //5. 合并图片(保证执行完组里面的所有任务之后，在执行notify里面的block )
    dispatch_group_notify(group, queue, ^{
        
        //1）开启一个位图上下文
        UIGraphicsBeginImageContextWithOptions(image.size, NO, 0.0);
        
        //2) 绘制第一张和第二张图
        [image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)];
        [image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height * 0.5)];
        
        //3) 得到上下文中的图片
        UIImage *fullImage = UIGraphicsGetImageFromCurrentImageContext();
        
        //4) 结束上下文
        UIGraphicsEndImageContext();
        
        //5. 回到主线程中加载UI
        dispatch_async(dispatch_get_main_queue(), ^{
            
            imageView.image = fullImage;
        });
    });

}

@end