我正在使用NSTask,但是当我启动任务时,它会阻止主线程(所以我无法更新它),直到任务结束.这是我的代码：
NSString *hostsforping = @"google.es";
pingdata = [[NSTask alloc] init];
[pingdata setLaunchPath: @"/sbin/ping"];
NSArray *pingargs;
pingargs = [NSArray arrayWithObjects: @"-c 5",hostsforping,nil];
[pingdata setArguments: pingargs];
NSPipe *pingpipe;
pingpipe = [NSPipe pipe];
[pingdata setStandardOutput: pingpipe];
NSFileHandle *pingfile;
pingfile = [pingpipe fileHandleForReading];
[pingdata launch];
NSData *pingdata1;
pingdata1 = [pingfile readDataToEndOfFile];
NSString *pingstring;
pingstring = [[NSString alloc] initWithData: pingdata1 encoding: NSUTF8StringEncoding];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(taskDidTerminate:)
name:NSTaskDidTerminateNotification
object:nil];
}
- (void) taskDidTerminate:(NSNotification *)notification {
NSLog(@"end");
}
我一直在读-waitUntilExit会阻塞主线程,但我没有使用它,所以我不知道我做错了什么.
解决方法
在后台线程上运行任务,readDataToEndOfFile阻塞主线程.
// Offload the method onto a background thread,could also use Grand Central Dispatch
[self performSelectorInBackground:@selector(startTask) withObject:nil];
- (void)startTask {
NSString *hostsforping = @"google.es";
NSTask *pingdata = [[NSTask alloc] init];
[pingdata setLaunchPath: @"/sbin/ping"];
NSArray *pingargs;
pingargs = [NSArray arrayWithObjects: @"-c 5",nil];
[pingdata setArguments: pingargs];
NSPipe *pingpipe;
pingpipe = [NSPipe pipe];
[pingdata setStandardOutput: pingpipe];
NSFileHandle *pingfile;
pingfile = [pingpipe fileHandleForReading];
[pingdata launch];
NSData *pingdata1;
pingdata1 = [pingfile readDataToEndOfFile];
NSString *pingstring;
pingstring = [[NSString alloc] initWithData: pingdata1 encoding: NSUTF8StringEncoding];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(taskDidTerminate:)
name:NSTaskDidTerminateNotification
object:nil];
}
- (void) taskDidTerminate:(NSNotification *)notification {
// Note this is called from the background thread,don't update the UI here
NSLog(@"end");
// Call updateUI method on main thread to update the user interface
[self performSelectorOnMainThread:@selector(updateUI) withObject:nil waitUntilDone:NO];
}
