- (void)updateLabel:(NSNumber *)aObject
{
self.displayLabel.text = [aObject stringValue];
NSLog(@"is duo xiancheng = %@",[[NSNumber numberWithBool:[NSThread isMultiThreaded]] stringValue]);
}


int n = 200000000;


- (void)compute:(NSNumber *)aObject
{
double sum = 0;
for (int a = aObject.intValue; a < n ; a++)
{
sum = sum + a;
// [self print:a];
}
[self performSelectorOnMainThread:@selector(updateLabel:) withObject:[NSNumber numberWithDouble:sum] waitUntilDone:NO];
}


- (void)thread1
{
[NSThread detachNewThreadSelector:@selector(compute:) toTarget:self withObject:[NSNumber numberWithInt:i]];
}


- (void)thread2
{
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

//group
dispatch_group_t group = dispatch_group_create();
dispatch_group_async(group, queue, ^{
double sum = 0;
for (int a = i; a < n ; a++)
{
sum = sum + a;
}
NSLog(@"queue 1 = %f",sum);
});

dispatch_barrier_async(queue, ^{
double sum = 0;
for (int a = i; a < n ; a++)
{
sum = sum + a;
}
NSLog(@"barrier = %f",sum);
});

dispatch_group_async(group, queue, ^{
double sum = 0;
for (int a = i; a < n ; a++)
{
sum = sum + a;
}
NSLog(@"queue 2 = %f",sum);
});



dispatch_group_async(group, queue, ^{
double sum = 0;
for (int a = i; a < n ; a++)
{
sum = sum + a;
}
NSLog(@"queue 3 = %f",sum);
});

dispatch_group_notify(group, dispatch_get_main_queue(), ^{
self.displayLabel.text = @"all done";
});


//async
// dispatch_async(queue, ^{
// double sum = 0;
// for (int a = i; a < n ; a++)
// {
// sum = sum + a;
//// [self print:a];
// }
// dispatch_async(dispatch_get_main_queue(), ^{
// self.displayLabel.text = [NSString stringWithFormat:@"%f",sum];
// NSLog(@"is duo xiancheng = %@",[[NSNumber numberWithBool:[NSThread isMultiThreaded]] stringValue]);
// });
// });

//
dispatch_async(queue, ^{
double sum = 0;
for (int a = i; a < n ; a++)
{
sum = sum + a;
}
NSLog(@"barrier queue 1 = %f",sum);
});

dispatch_async(queue, ^{
double sum = 0;
for (int a = i; a < n ; a++)
{
sum = sum + a;
}
NSLog(@"barrier = %f",sum);
});

dispatch_async(queue, ^{
double sum = 0;
for (int a = i; a < n ; a++)
{
sum = sum + a;
}
NSLog(@"barrier queue 2 = %f",sum);
});



dispatch_async(queue, ^{
double sum = 0;
for (int a = i; a < n ; a++)
{
sum = sum + a;
}
NSLog(@"barrier queue 3 = %f",sum);
});
}


- (void)thread3
{
NSMethodSignature *sig = [self methodSignatureForSelector:@selector(compute:)];
NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:sig];
[invocation setTarget:self];
[invocation setSelector:@selector(compute:)];
NSNumber *num = [NSNumber numberWithInt:i];
[invocation setArgument:&num atIndex:2];
NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithInvocation:invocation];
//[[NSInvocationOperation alloc] initWithTarget:self selector:@selector(compute:) object:];

NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[queue addOperation:operation];
}


- (void)thread4
{
NSThread *thread = [[NSThread alloc] initWithTarget:self selector:@selector(compute:) object:[NSNumber numberWithInt:i]];
[thread start];
}


- (void)thread5
{
[self performSelectorInBackground:@selector(compute:) withObject:[NSNumber numberWithInt:i]];
}