NSOperation

// 同步执行的代码
NSInvocationOperation * invocationOp = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(invocationRun) object:nil]; [invocationOp start];

NSBlockOperation * blockOp = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"blockOpRun_0");
}];
[blockOp start];

//这个是异步操作
[blockOp addExecutionBlock:^{
NSLog(@"blockOpRun_1");
}];
//这个是异步操作
[blockOp addExecutionBlock:^{
NSLog(@"blockOpRun_2");
}];
//这个是异步操作
[blockOp addExecutionBlock:^{
NSLog(@"blockOpRun_3");
}];
//这个是异步操作
[blockOp addExecutionBlock:^{
NSLog(@"blockOpRun_4");
}];
[blockOp start];