如何在NSStream中使用委托？ [英] How to use delegate in NSStream?

问题描述

我是Objective-C的新手。我正在尝试学习如何使用 NSStream 。我刚刚使用Apple Support的简单代码。该代码应该从桌面中的文件打开一个流，并在iStream调用委托时显示一条简单的消息。在代码的最后，我可以看到状态是正确的，但代理从来没有被调用。我缺少什么？

  #import< Foundation / Foundation.h> 
 
 @interface MyDelegate：NSStream< NSStreamDelegate> {
} 
 
  - （void）stream：（NSStream *）stream handleEvent：（NSStreamEvent）eventCode; 
 
 @end 
 
 @implementation MyDelegate 
 
  - （void）stream：（NSStream *）stream handleEvent：（NSStreamEvent）eventCode {
 NSLog（@############ DELEGATE ##############）; 
} 
 
 @end 
 
 int main（int argc，const char * argv []）
 {
 @autoreleasepool {
 MyDelegate * myDelegate = [[MyDelegate alloc] init]; 
 NSInputStream * iStream = [[NSInputStream alloc] initWithFileAtPath：@/ Users / Augend / Desktop / Test.rtf]; 
 
 [iStream setDelegate：myDelegate]; 
 
 [iStream scheduleInRunLoop：[NSRunLoop currentRunLoop] 
 forMode：NSDefaultRunLoopMode]; 
 [iStream open]; 
 
 NSLog（@status：％@，（NSString *）[iStream streamError]）; 
} 
 return 0; 
} 
  

解决方案

运行循环不是运行足够长的代理方法被调用。

添加：

  [[NSRunLoop currentRunLoop] runUntilDate：[NSDate dateWithTimeIntervalSinceNow：2.0]];打开流后，
  

。这只是在没有GUI的程序中才需要的 - 否则运行循环将为你而生。

如果你想绝对确定 stream：handleEvent：在退出之前被调用，在该方法中设置一个（全局）标志，并将 runUntilDate：在 while 循环测试标志：

  while（！delegateHasBeenNotified）{
 [[NSRunLoop currentRunLoop] runUntilDate：[NSDate dateWithTimeIntervalSinceNow：0.5]]; 
} 
  

I am a newbie in Objective-C. I am trying to learn how to work with NSStream. I just used simple code from Apple Support. This code should open a stream from a file in my Desktop and show a simple message when the delegate is called by iStream. At the end of the code, I can see the status is correct, but the delegate never gets called. What am I missing?

#import <Foundation/Foundation.h>

@interface MyDelegate: NSStream <NSStreamDelegate>{
}

- (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)eventCode ;

@end

@implementation MyDelegate

- (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)eventCode  {
    NSLog(@"############# in DELEGATE###############");
}

@end

int main(int argc, const char * argv[])
{
    @autoreleasepool {
        MyDelegate* myDelegate=[[MyDelegate alloc]init];
        NSInputStream* iStream= [[NSInputStream alloc] initWithFileAtPath:@"/Users/Augend/Desktop/Test.rtf"];

        [iStream setDelegate:myDelegate];

        [iStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
                           forMode:NSDefaultRunLoopMode];
        [iStream open];

        NSLog(@" status:%@",(NSString*) [iStream streamError]);
    }
    return 0;
}

解决方案

The run loop isn't running long enough for the delegate method to be called.

Add:

[[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:2.0]];

right after you open the stream. This is only necessary in a program without a GUI -- otherwise the run loop would be spun for you.

If you want to be absolutely sure that stream:handleEvent: has been called before exiting, set a (global) flag in that method and put the runUntilDate: in a while loop that tests for the flag:

while( !delegateHasBeenNotified ){
     [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:0.5]];
}

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