如何使用 dataTaskWithURL:completionHandler 从 PHP 调用检索

Question

我可以在下面的代码中使用 dataTaskWithURL:completionHandler 吗：

// to call data if there are comments

NSString *checkTitle = self.currentList.qasidaId;
NSLog(@"%@ the title: ", self.currentList.qasidaId);

NSString *url = [NSString stringWithFormat:@"http:/MyWebSite/checkphp.php?title=%@", checkTitle];
NSData *data =[[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:[url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]];


self.jasonArray = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
self.listArray = [[NSMutableArray alloc]init];

for (int i = 0; i < self.jasonArray.count; i++) {
NSString *cUserName = [[self.jasonArray objectAtIndex:i]objectForKey:@"userName"];
NSString *cTitle = [[self.jasonArray objectAtIndex:i]objectForKey:@"title"];
NSString *cComments = [[self.jasonArray objectAtIndex:i]objectForKey:@"comments"];
NSString *cTimeC = [[self.jasonArray objectAtIndex:i]objectForKey:@"commentsTime"];
NSString *cDateC = [[self.jasonArray objectAtIndex:i]objectForKey:@"commentsDate"];
NSString *cUserNameArabicC = [[self.jasonArray objectAtIndex:i]objectForKey:@"commentsDate"];
NSString *cTheUserIdC = [[self.jasonArray objectAtIndex:i]objectForKey:@"theUserId"];


[self.listArray addObject:[[ListOfObjects alloc]initWithUserName:cUserName andTitle:cTitle andComments:cComments andtimeC:cTimeC andDateC:cDateC andUserNameArabicC:cUserNameArabicC andTheUserIdC:cTheUserIdC]];

}

[self.tableView reloadData];

}

我需要在上面的代码中使用 dataTaskWithURL:completionHandler，我需要更改什么？

谢谢

Answer 1

您想使用 dataTaskWithURL 并将所有解析逻辑和 table 重新加载逻辑放在 completionHandler 块中：

NSString *checkTitle = self.currentList.qasidaId;
NSLog(@"%@ the title: ", self.currentList.qasidaId);

NSString *urlString = [NSString stringWithFormat:@"http://MyWebSite/checkphp.php?title=%@", checkTitle];
NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

NSURLSessionTask *task = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    if (!data) { 
        NSLog(@"connection error: %@", error);
        return;
    }

    NSError *parseError;
    NSArray *json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&parseError];
    if (!json) {
        NSLog(@"JSON Parsing error: %@", parseError);
        NSLog(@"data = %@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
        return;
    }

    NSMutableArray *results = [[NSMutableArray alloc]init];

    for (int i = 0; i < json.count; i++) {
        NSString *cUserName        = json[i][@"userName"];
        NSString *cTitle           = json[i][@"title"];
        NSString *cComments        = json[i][@"comments"];
        NSString *cTimeC           = json[i][@"commentsTime"];
        NSString *cDateC           = json[i][@"commentsDate"];
        NSString *cUserNameArabicC = json[i][@"commentsDate"];
        NSString *cTheUserIdC      = json[i][@"theUserId"];

        [results addObject:[[ListOfObjects alloc]initWithUserName:cUserName andTitle:cTitle andComments:cComments andtimeC:cTimeC andDateC:cDateC andUserNameArabicC:cUserNameArabicC andTheUserIdC:cTheUserIdC]];
    }

    dispatch_async(dispatch_get_main_queue(), ^{
        self.listArray = results;
        [self.tableView reloadData];
    });
}];
[task resume];

// Just remember, by the time you get here, the above request is
// *not* done. That's why we do the `reloadData` inside the block
// above, and not here.

注意，completionHandler 块 (a) 异步运行； (b) 在后台线程上运行。后一点是为什么我不更新任何 class 属性或从后台线程更新 UI，而是在我们完成解析后手动调用 dispatch_async 回到主线程，其中 (a) 更新 listArray 和 (b) 执行 tableView

的 reloadData

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