TWRequest Crash

twrequest_crash.m

// This code works:

TWRequest *request = [[TWRequest alloc] initWithURL:[NSURL URLWithString:@"http://api.twitter.com/1/statuses/home_timeline.json"]
											 parameters:nil
										  requestMethod:TWRequestMethodGET];

// But this code crashes:

TWRequest *request = [[TWRequest alloc] initWithURL:[NSURL URLWithString:@"http://api.twitter.com/1/statuses/home_timeline.json"]
											 parameters:@{@"count":@(200)}
										  requestMethod:TWRequestMethodGET];

// The log shows:
// -[__NSCFNumber length]: unrecognized selector sent to instance 0x9c6e060