- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
[self downloadImage];
}
-(void)downloadImage{
dispatch_group_t group = dispatch_group_create();
dispatch_queue_t queue = dispatch_get_global_queue(, );
dispatch_group_async(group, queue, ^{
NSURL *url = [NSURL URLWithString:@"https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1530167525247&di=f09b0f4412a2825e4ae641079691cd14&imgtype=0&src=http%3A%2F%2Fpic35.photophoto.cn%2F20150617%2F0013026499624253_b.png"];
NSData *data = [NSData dataWithContentsOfURL:url];
self.image1 = [UIImage imageWithData:data];
});
dispatch_group_async(group, queue, ^{
NSURL *url = [NSURL URLWithString:@"https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1530167525247&di=184be5b28b34bf0670e9cb065fef673c&imgtype=0&src=http%3A%2F%2Fpic22.nipic.com%2F20120724%2F16351_204302573152_2.png"];
NSData *data = [NSData dataWithContentsOfURL:url];
self.image2 = [UIImage imageWithData:data];
});
dispatch_group_notify(group,queue , ^{
//1创建图形上下文
UIGraphicsBeginImageContext(CGSizeMake(, ));
//2.画图
[self.image1 drawInRect:CGRectMake(, , , )];
self.image1 = nil;//此时不需要图片了
//3.画图
[self.image2 drawInRect:CGRectMake(, , , )];
self.image2 = nil;//此时不需要图片了
//4.从图形上下文获取图片
UIImage *tempImage = UIGraphicsGetImageFromCurrentImageContext();
//5.关闭上下文
UIGraphicsEndImageContext();
//6更新UI
dispatch_async(dispatch_get_main_queue(), ^{
self.imageView.image = tempImage;
});
});
}
swift 版 下载图片
//保证 下载完图片在分享
private func getDownloadImage(urlStrArr:[String], block:@escaping (_ imageArr:[UIImage])->()){
var downloadImageArr : [UIImage] = []
var tempBlock : ((_ imageArr:[UIImage])->())? = nil
tempBlock = block
let group = DispatchGroup()
let diyQueue = DispatchQueue(label: "diyQueue") for (_, urlStr) in urlStrArr.enumerated(){
group.enter()
diyQueue.async {
if let tempUrl = URL.init(string: urlStr){
if let tempData = try? Data.init(contentsOf: tempUrl){
if let tempImage = UIImage.init(data: tempData){
downloadImageArr.append(tempImage)
group.leave()
}
}
}
}
} //走完队列
group.notify(queue: diyQueue) { //这个地方可以合并数据, 图片合并操作等等
//主线程刷新
DispatchQueue.main.async {
tempBlock?(downloadImageArr)
}
}
}
调用
getDownloadImage(urlStrArr: [dataStruct.relationQrCodeUrl]) { [weak self](imageArr:[UIImage]) in
self?.downloadView.updateImage(downImage: imageArr[])
}