UISearchDisplayController-等待N秒钟，或者让用户按"Search"(搜索)在进行搜索之前 [英] UISearchDisplayController - wait for N seconds OR for user to press "Search" before conducting search

问题描述

我有一个UISearchDisplayController，目前我后悔执行.问题是我的搜索控制器访问Web服务，然后通过调用[tableView reloadData]更新UITableView.每次用户输入密钥时，它都会进行搜索.通过调用ASIHTTPRequest至少需要三个字符，我已经能够部分缓解症状，但是必须有更好的方法.基本上，我希望UISearchDisplayController等待N秒，或者让用户在搜索之前按搜索".这是我现在拥有的:

I have a UISearchDisplayController that I am currently regretting implementing. The problem is that my search controller accesses a web service and then updates a UITableView by calling [tableView reloadData]. Every time a user enters a key, it searches. I've been able to partially relieve the symptoms by requiring at least three characters before calling the ASIHTTPRequest but there must be a better way. Basically I want the UISearchDisplayController to wait for N seconds OR for the user to press "Search" before searching. Here's what I have now:

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString {

    if (searchString.length > 2) {

        ASIHTTPRequest *request = [IKRequestBuilder requestForIKDogFoodWithQueryString:searchString];
        [request setDelegate:self];
        [request startAsynchronous];
    }   

    return NO;
}

#pragma mark - ASI HTTP Request

- (void)requestStarted:(ASIHTTPRequest *)request {
    //show activity view over table view
}

- (void)requestFinished:(ASIHTTPRequest *)request {
    NSString *response = [request responseString];
    self.dogFoods = [IKJsonFactory buildIKDogFoodArrayWithJSON:response];
    [self.searchDisplayController.searchResultsTableView reloadData];
}

推荐答案

将NSTimer作为属性添加到搜索委托中.

Add an NSTimer as a property on your search delegate.

在shouldReloadTableForSearchString:(NSString *)searchString委托方法中，不要立即发送请求，而是要检查是否已经有一个计时器，如果要取消它，则启动一个新计时器.

In the shouldReloadTableForSearchString:(NSString *)searchString delegate method, instead of sending the request straight away, instead check if you have a timer already, if so cancel it, then start a new timer.

在计时器的目标方法中，开始搜索.

In the timer's target method, kick off the search.

这意味着在他们键入内容时，您将继续创建计时器.当他们停止键入时，计时器的最后一个角色将在n秒内触发.然后，您只需要在他们按下按钮时添加手动开始的搜索即可. (您还可以添加一个布尔值，以检查搜索是否已经开始).

This will mean that while they are typing you will keep recreating the timer. When they stop typing the last incarnation of the timer will fire in n seconds. Then you just need to also add the manual kicking off of the search when they press the button. (you could also add a boolean to check if the search has already been started).

即在您的代表界面中

NSTimer *searchTimer;

@property (nonatomic, retain) NSTimer *searchTimer;

然后在您的shouldReloadTableForSearchString的实现中，而不是触发Web请求，请执行以下操作:

Then in your implementation of the shouldReloadTableForSearchString, instead of firing off the web request, do this:

if (self.searchTimer) {
    [self.searchTimer invalidate];
    self.searchTimer = nil;
}
self.searchTimer = [NSTimer scheduledTimerWithTimeInterval:2 target:self selector:@selector(searchTimerPopped:) userInfo:nil repeats:FALSE];

然后在您的计时器目标中

Then in your timer target

-(void) searchTimerPopped:(NSTimer *)sTimer {
    // code to fire off the asynchronous web call to do the search
}

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