How to Select from two tables in 1 query in Salesforce SOQL iOS

Question

How can i combine this two request in salesforce SOQL query into 1 single request in iOS:

NSString *theRequest = [NSString stringWithFormat:@"SELECT Name, OpportunityID FROM OpportunityLineItem where OpportunityID = '%@'", [companyDic objectForKey:@"Id"]];
SFRestRequest *request = [[SFRestAPI sharedInstance] requestForQuery:theRequest];
[[SFRestAPI sharedInstance] send:request delegate:self];

and

NSString *theRequest2 = [NSString stringWithFormat:@"SELECT CompetitorName FROM OpportunityCompetitor where OpportunityID = '%@'", [companyDic objectForKey:@"Id"]];
SFRestRequest *request2 = [[SFRestAPI sharedInstance] requestForQuery:theRequest2];
[[SFRestAPI sharedInstance] send:request2 delegate:self];

Answer 1

Use this subquery:

SELECT Name, OpportunityID FROM OpportunityLineItem where OpportunityID IN (SELECT OpportunityID FROM OpportunityCompetitor where OpportunityID = '%@')