IOS线程相关

1、 子线程更新主线程的一种方式

    // Perform GUI update on main thread

    [[NSOperationQueuemainQueue] addOperationWithBlock:^(){

       textView.text =log;

    }];

2、计算运行了多少秒

NSDate *startDate = [NSDate date];

//其它内容

NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url];

NSURLResponse *response;

NSError *error;

    success = NO;

    

NSData* result = [NSURLConnection sendSynchronousRequest:theRequest returningResponse:&response error:&error];

[self log:@"Elapsed time: %0.2f seconds.", [[NSDate date] timeIntervalSinceDate:startDate]];