03-隊列組 (瞭解)

  1 #import "XZViewController.h"
  2 
  3 // 1.分別下載2張圖片：大圖片、LOGO
  4 // 2.合併2張圖片
  5 // 3.顯示到一個imageView身上
  6 
  7 @interface XZViewController ()
  8 @property (weak, nonatomic) IBOutlet UIImageView *imageView;
  9 @property (nonatomic, strong) UIImage *image1;
 10 @property (nonatomic, strong) UIImage *image2;
 11 @end
 12 
 13 @implementation XZViewController
 14 
 15 - (void)viewDidLoad
 16 {
 17     [super viewDidLoad];
 18     
 19 }
 20 
 21 // 2D繪圖  Quartz2D
 22 // 合併圖片 -- 水印
 23 
 24 - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
 25 {   // 方法三
 26     // 1.隊列組
 27     dispatch_group_t group = dispatch_group_create();
 28     dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
 29     
 30     // 2.下載圖片1
 31     __block UIImage *image1 = nil;
 32     dispatch_group_async(group, queue, ^{
 33         NSURL *url1 = [NSURL URLWithString:@"http://g.hiphotos.baidu.com/image/pic/item/f2deb48f8c5494ee460de6182ff5e0fe99257e80.jpg"];
 34         NSData *data1 = [NSData dataWithContentsOfURL:url1];
 35         image1 = [UIImage imageWithData:data1];
 36     });
 37     
 38     // 3.下載圖片2
 39     __block UIImage *image2 = nil;
 40     dispatch_group_async(group, queue, ^{
 41         NSURL *url2 = [NSURL URLWithString:@"http://su.bdimg.com/static/superplus/img/logo_white_ee663702.png"];
 42         NSData *data2 = [NSData dataWithContentsOfURL:url2];
 43         image2 = [UIImage imageWithData:data2];
 44     });
 45     
 46     // 4.合併圖片 (保證執行完組裡面的所有任務之後，再執行notify函數裡面的block)
 47     dispatch_group_notify(group, queue, ^{
 48         // 開啟一個點陣圖上下文
 49         UIGraphicsBeginImageContextWithOptions(image1.size, NO, 0.0);
 50         
 51         // 繪製第1張圖片
 52         CGFloat image1W = image1.size.width;
 53         CGFloat image1H = image1.size.height;
 54         [image1 drawInRect:CGRectMake(0, 0, image1W, image1H)];
 55         
 56         // 繪製第2張圖片
 57         CGFloat image2W = image2.size.width * 0.5;
 58         CGFloat image2H = image2.size.height * 0.5;
 59         CGFloat image2Y = image1H - image2H;
 60         [image2 drawInRect:CGRectMake(0, image2Y, image2W, image2H)];
 61         
 62         // 得到上下文中的圖片
 63         UIImage *fullImage = UIGraphicsGetImageFromCurrentImageContext();
 64         
 65         // 結束上下文
 66         UIGraphicsEndImageContext();
 67         
 68         // 5.回到主線程顯示圖片
 69         dispatch_async(dispatch_get_main_queue(), ^{
 70             self.imageView.image = fullImage;
 71         });
 72     });
 73 }
 74 /** 方法二  */
 75 - (void)test2
 76 {
 77     // 非同步下載
 78     dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
 79         // 1.下載第1張
 80         NSURL *url1 = [NSURL URLWithString:@"http://g.hiphotos.baidu.com/image/pic/item/f2deb48f8c5494ee460de6182ff5e0fe99257e80.jpg"];
 81         NSData *data1 = [NSData dataWithContentsOfURL:url1];
 82         self.image1 = [UIImage imageWithData:data1];
 83         
 84         [self bindImages];
 85     });
 86     dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
 87         // 2.下載第2張
 88         NSURL *url2 = [NSURL URLWithString:@"http://su.bdimg.com/static/superplus/img/logo_white_ee663702.png"];
 89         NSData *data2 = [NSData dataWithContentsOfURL:url2];
 90         self.image2 = [UIImage imageWithData:data2];
 91         
 92         [self bindImages];
 93     });
 94 }
 95 
 96 - (void)bindImages
 97 {
 98     if (self.image1 == nil || self.image2 == nil) return;
 99     
100     // 3.合併圖片
101     // 開啟一個點陣圖上下文
102     UIGraphicsBeginImageContextWithOptions(self.image1.size, NO, 0.0);
103     
104     // 繪製第1張圖片
105     CGFloat image1W = self.image1.size.width;
106     CGFloat image1H = self.image1.size.height;
107     [self.image1 drawInRect:CGRectMake(0, 0, image1W, image1H)];
108     
109     // 繪製第2張圖片
110     CGFloat image2W = self.image2.size.width * 0.5;
111     CGFloat image2H = self.image2.size.height * 0.5;
112     CGFloat image2Y = image1H - image2H;
113     [self.image2 drawInRect:CGRectMake(0, image2Y, image2W, image2H)];
114     
115     // 得到上下文中的圖片
116     UIImage *fullImage = UIGraphicsGetImageFromCurrentImageContext();
117     
118     // 結束上下文
119     UIGraphicsEndImageContext();
120     
121     // 4.回到主線程顯示圖片
122     dispatch_async(dispatch_get_main_queue(), ^{
123         self.imageView.image = fullImage;
124     });
125 }
126 /** 方法一 */
127 - (void)test1
128 {
129     // 非同步下載
130     dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
131         // 1.下載第1張
132         NSURL *url1 = [NSURL URLWithString:@"http://g.hiphotos.baidu.com/image/pic/item/f2deb48f8c5494ee460de6182ff5e0fe99257e80.jpg"];
133         NSData *data1 = [NSData dataWithContentsOfURL:url1];
134         UIImage *image1 = [UIImage imageWithData:data1];
135         
136         // 2.下載第2張
137         NSURL *url2 = [NSURL URLWithString:@"http://su.bdimg.com/static/superplus/img/logo_white_ee663702.png"];
138         NSData *data2 = [NSData dataWithContentsOfURL:url2];
139         UIImage *image2 = [UIImage imageWithData:data2];
140         
141         // 3.合併圖片
142         // 開啟一個點陣圖上下文
143         UIGraphicsBeginImageContextWithOptions(image1.size, NO, 0.0);
144         
145         // 繪製第1張圖片
146         CGFloat image1W = image1.size.width;
147         CGFloat image1H = image1.size.height;
148         [image1 drawInRect:CGRectMake(0, 0, image1W, image1H)];
149         
150         // 繪製第2張圖片
151         CGFloat image2W = image2.size.width * 0.5;
152         CGFloat image2H = image2.size.height * 0.5;
153         CGFloat image2Y = image1H - image2H;
154         [image2 drawInRect:CGRectMake(0, image2Y, image2W, image2H)];
155         
156         // 得到上下文中的圖片
157         UIImage *fullImage = UIGraphicsGetImageFromCurrentImageContext();
158         
159         // 結束上下文
160         UIGraphicsEndImageContext();
161         
162         // 4.回到主線程顯示圖片
163         dispatch_async(dispatch_get_main_queue(), ^{
164             self.imageView.image = fullImage;
165         });
166     });
167 }
168 
169 @end