03-隊列組 (瞭解)，03-隊列組瞭解

03-隊列組 (瞭解)，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.合并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 // 合并圖片 -- 浮水印 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.合并圖片 (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         // 開啟一個位元影像上下文 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.合并圖片101     // 開啟一個位元影像上下文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)test1128 {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.合并圖片142         // 開啟一個位元影像上下文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