Question

我在故事板中的视图上设置了 UIButton ，并链接到某个操作。该操作运行一些代码，通过NSURLSessionDataTask调用PHP页面（然后在MySql DB中记录记录）。

当我触摸按钮一次并在XCode的日志屏幕中看到日志打印时，我可以看到我的打印消息一次，但如果我检查MySql DQ，我可以看到插入了多个相同的记录。

我起初认为可能是PHP代码，但如果我直接通过网络浏览器加载php页面，我就不会遇到问题，只有在通过ios代码运行时才会出现问题。

反正停止按钮代码执行的次数是多少？

来自UIButtons行动的代码：

- (void)UpdateActions{

    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://xxx/mobilescript/setactions.php"]];
    [request setHTTPMethod:@"POST"];
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"content-type"];

    NSString *postString = [[NSString alloc] initWithFormat:@"imgname=%@",imageName];
    NSString *clearPost = [postString stringByReplacingOccurrencesOfString:@"var=" withString:@""];

    [request setHTTPBody:[clearPost dataUsingEncoding:NSUTF8StringEncoding]];
    [request setValue:clearPost forHTTPHeaderField:@"Content-Length"];
    [NSURLConnection connectionWithRequest:request delegate:self];

    NSURLSession *session = [NSURLSession sharedSession];

     NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

        NSString * returnStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
        NSLog(@"%@",returnStr);
    }];
    [task resume];
}

PHP代码：

<?php
    include_once("DB_SETTING.php"); //Includes DB settings

    $DB_HANDLE = mysql_connect( "$DB_SERVER" , "$DB_USERNAME" , "$DB_PASSWORD" ) or $errors[] = mysql_error();
    if(!mysql_select_db( "$DB_NAME" ))
    {
        $errors[] = "Unable to select database $DB_NAME";
    } 

    if($errors){
        echo '<pre>';
        foreach($errors as $result) {
            echo $result . ' <br>';
        }
        echo '</pre>';
    }

    //Check all settings are in place
    if(!isset($_REQUEST["imgname"]) )
    {
        echo("-1");
    }
    else
    {
            $sql = "INSERT INTO  `WS_ACTIONS` (  `ID` ,  `imgid` ,`memberid` ) 

                    SELECT 0,tb3.id,tb2.id FROM  WS_MEMBERS tb2,WS_IMAGES tb3 WHERE `IMGNAME` = '".$_REQUEST["imgname"]."' and tb2.email = '".$_REQUEST["email"]."' And NOT EXISTS (
            SELECT 
                tb1.ID 
            FROM 
                WS_ACTIONS tb1 
            inner join 
                WS_IMAGES tb2 
            on 
                tb2.id = tb1.imgid
            inner join 
                WS_MEMBERS tb3
            on 
                tb3.id = tb1.memberid
            where 
                imgname = '".$_REQUEST["imgname"]."' 
            and 
                tb3.email = '".$_REQUEST["email"]."' 
            )";
            mysql_query($sql);
            echo($sql);
    }
?>

Answer 1

如果您有按钮实例，则可以启用/禁用它。其他解决方案是创建一个BOOL来保持按钮是否应该执行某些事情

示例：

- (void)UpdateActions{ NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://xxx/mobilescript/setactions.php"]]; [request setHTTPMethod:@"POST"]; [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"content-type"]; NSString *postString = [[NSString alloc] initWithFormat:@"imgname=%@",imageName]; NSString *clearPost = [postString stringByReplacingOccurrencesOfString:@"var=" withString:@""]; [request setHTTPBody:[clearPost dataUsingEncoding:NSUTF8StringEncoding]]; [request setValue:clearPost forHTTPHeaderField:@"Content-Length"]; [NSURLConnection connectionWithRequest:request delegate:self]; NSURLSession *session = [NSURLSession sharedSession]; // disable your button if you have a reference to it [self.yourBtn setEnabled:NO]; // or set your BOOL to NO here NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) { // regardless of the response once your request had finished just enable your button again [self.yourBtn setEnabled:YES]; // or set your BOOL to YES here NSString * returnStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; NSLog(@"%@",returnStr); }]; [task resume]; }

修改您可以尝试使用NSURLConnection，而不是这样：

- (void)UpdateActions{ NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://xxx/mobilescript/setactions.php"]]; [request setHTTPMethod:@"POST"]; [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"content-type"]; NSString *postString = [[NSString alloc] initWithFormat:@"imgname=%@",imageName]; NSString *clearPost = [postString stringByReplacingOccurrencesOfString:@"var=" withString:@""]; [request setHTTPBody:[clearPost dataUsingEncoding:NSUTF8StringEncoding]]; [request setValue:clearPost forHTTPHeaderField:@"Content-Length"]; [NSURLConnection connectionWithRequest:request delegate:self]; // disable your button if you have a reference to it [self.yourBtn setEnabled:NO]; // or set your BOOL to NO here // create NSOperation to run your request on background NSOperationQueue *queue = [[NSOperationQueue alloc]init]; // run your request on this peration queue [NSURLConnection sendAsynchronousRequest:request queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) { NSString * returnStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; NSLog(@"%@",returnStr); // do whatever you want with the response [[NSOperationQueue mainQueue] addOperationWithBlock:^{ // Main thread work (UI usually) [self.yourBtn setEnabled:YES]; }]; }]; }

Answer 2

问题是您正在向服务器发起两个请求。使用此行创建请求时，

[NSURLConnection connectionWithRequest:request delegate:self];

这会立即从您的服务器开始下载。然后，通过使用此行创建NSURLSessionDataTask（然后调用[task resume]），从服务器开始另一次下载，

NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

如果你正在使用NSURLSession，你也不应该调用connectionWithRequest：delegate：，所以删除该行应该可以解决你的问题。

防止UIButton操作多次运行

2 个答案: