在PhoneGap插件中保留回调上下文？ [英] Keep callback context in PhoneGap plugin?

问题描述

我需要实现一些功能，在一个间隔触发一个动作，并将结果发送回javascript。

为了简化，我将使用PhoneGap文档中的echo示例：

   - （void）echo：（CDVInvokedUrlCommand *）命令
 {
 [self.commandDelegate runInBackground：^ {
 
 CDVPluginResult * pluginResult =零; 
 NSString * echo = [command.arguments objectAtIndex：0]; 
 
 if（echo！= nil&& [echo length]> 0）{
 pluginResult = [CDVPluginResult resultWithStatus：CDVCommandStatus_OK messageAsString：echo]; 
} else {
 pluginResult = [CDVPluginResult resultWithStatus：CDVCommandStatus_ERROR]; 
} 
 
 [self.commandDelegate sendPluginResult：pluginResult callbackId：command.callbackId]; 
 
}]; 
} 
  

我想让这个调用与echo

我创建了一个定时器，每秒钟调用另一个函数，但我不知道如何保持回调的上下文发送结果。

  //开始计时
  - （void）start：（CDVInvokedUrlCommand *）command 
 {
 [NSTimer scheduledTimerWithTimeInterval：1.0 
 target：self 
 selector：@selector（action :) 
 userInfo：nil 
重复：YES]; 
} 
 
 //调用的操作
  - （void）action：（CDVInvokedUrlCommand *）command 
 {
 [self.commandDelegate runInBackground：^ {
 
 NSLog（@TRIGGERED）; 
 
}]; 
} 
  

任何帮助保持这个在回调的上下文中将是巨大的。非常感谢！

解决方案

您会想要：

  NSString * myCallbackId; 
  

作为实例级变量（在任何方法之外，因此它保留其值）。首次进入插件代码时设置：

  myCallbackId = command.callbackId;然后，在实例化一个PluginResult之后，但在使用它之前，做一些类似的操作：
 
  [pluginResult setKeepCallback：[NSNumber numberWithBool：YES]]; 
  
这会让回调有效以备将来使用。
 
 
 
然后执行如下操作：
  [self.commandDelegate sendPluginResult：pluginResult callbackId：myCallbackId]; 
  
 
I need to implement some functionality that triggers an action on an interval and emits the results back to javascript. 

To simplify things I will use the echo example from the PhoneGap documentation:
- (void)echo:(CDVInvokedUrlCommand*)command
{
  [self.commandDelegate runInBackground:^{

    CDVPluginResult* pluginResult = nil;
    NSString* echo = [command.arguments objectAtIndex:0];

    if (echo != nil && [echo length] > 0) {
        pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsString:echo];
    } else {
        pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_ERROR];
    }

    [self.commandDelegate sendPluginResult:pluginResult callbackId:command.callbackId];

  }];
}
I want to make this call the same callback with the echo every second until stop is called. 

I've created a timer that calls another function every second, but I don't know how to keep the context of the callback to send the result to. 
//Starts Timer
- (void)start:(CDVInvokedUrlCommand*)command
{
  [NSTimer scheduledTimerWithTimeInterval:1.0
                                  target:self
                                  selector:@selector(action:)
                                  userInfo:nil
                                  repeats:YES];
}

//Called Action
-(void)action:(CDVInvokedUrlCommand*)command
{
  [self.commandDelegate runInBackground:^{

    NSLog(@"TRIGGERED");

  }];
}
Any help keeping this within the context of the callback would be great. Thanks!
解决方案
You'll want to have something like:
NSString *myCallbackId;
as an instance-level variable (outside of any method, so it retains its value). Set it when you first come in to the plugin code:
myCallbackId = command.callbackId;
Then, right after you instantiate a PluginResult, but before using it, do something like:
[pluginResult setKeepCallback:[NSNumber numberWithBool:YES]];
That will tell it to keep the callback valid for future use.

Then do something like:
[self.commandDelegate sendPluginResult:pluginResult callbackId:myCallbackId];


                        
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