iOS GCD 图片合成效果(几张图片拼接在一起)~demo

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//GCD 图片合成效果:

#import"SHViewController.h"

@interfaceViewController()

@property(weak,nonatomic)IBOutletUIImageView*imageView;//视图 imageView

@property(nonatomic,strong)UIImage*image1;

@property(nonatomic,strong)UIImage*image2;

@end

@implementationSHViewController

- (void)viewDidLoad {

[superviewDidLoad];

[selfsyntheticImages];//合成图片

}

-(void)syntheticImages//合成图片

{

//创建队列组

dispatch_group_tgroup =dispatch_group_create();

//1.开子线程下载图片

//创建队列(并发)

dispatch_queue_tqueue =dispatch_get_global_queue(0,0);

//异步执行并发队列

dispatch_group_async(group, queue, ^{

//1.获取url地址

NSURL*url = [NSURLURLWithString:@"https://imgsa.baidu.com/baike/c0=baike180,5,5,180,60/sign=b531c24482025aafc73f76999a84c001/b21c8701a18b87d6435d2f9b070828381f30fd13.jpg"];

//2.下载图片

NSData*data = [NSDatadataWithContentsOfURL:url];

//3.把二进制数据转换成图片

self.image1= [UIImageimageWithData:data];

});

//下载图片2

dispatch_group_async(group, queue, ^{

//1.获取url地址

NSURL*url = [NSURLURLWithString:@"https://imgsa.baidu.com/baike/c0=baike220,5,5,220,73/sign=62c273b38a13632701e0ca61f0e6cb89/8644ebf81a4c510faae40d756059252dd42aa5b9.jpg"];

//2.下载图片

NSData*data = [NSDatadataWithContentsOfURL:url];

//3.把二进制数据转换成图片

self.image2= [UIImageimageWithData:data];

});

//合成

dispatch_group_notify(group, queue, ^{

//开启图形上下文

UIGraphicsBeginImageContext(CGSizeMake(200,200));

//画1

[self.image1drawInRect:CGRectMake(0,0,200,100)];

//画2[self.image2drawInRect:CGRectMake(0,100,200,100)];

//根据图形上下文拿到图片

UIImage*image =UIGraphicsGetImageFromCurrentImageContext();

//关闭上下文

UIGraphicsEndImageContext();

dispatch_async(dispatch_get_main_queue(), ^{

self.imageView.image= image;});});

}

@end