gistfile1.m

- (void)testLoginButtonTapped
{
	// mock a Server
	id serverMock = OCMClassMock([Server class]);
	
	OCMStub([serverMock loginUserWithName:[OCMArg any] password:[OCMArg any]]).andReturn(YES);
	_loginVC.serverToUse = serverMock;

	// simulate input in name field
	_loginVC.userTextField.text = @"foo";
	[_loginVC.userTextField sendActionsForControlEvents:UIControlEventEditingChanged];
	
	// simulate input in password field
	_loginVC.passwordTextField.text = @"bar";
	[_loginVC.passwordTextField sendActionsForControlEvents:UIControlEventEditingChanged];

	// simulate login button press
	[_loginVC.loginButton sendActionsForControlEvents:UIControlEventTouchUpInside];
	
	// verify it has called the expected method
	OCMVerify([serverMock loginUserWithName:[OCMArg checkWithBlock:^BOOL(NSString *obj) {
		return [obj isEqualToString:@"foo"];
	}] password:[OCMArg any]]);
}

see https://gist.github.com/Cocoanetics/b2d80c4816d0de1cd207