iOS SQLite FMDB Transactions.. Correct usage?

You could also use FMDatabaseQueue to handle your transactions, which is part of fmdb:

[queue inTransaction:^(FMDatabase *db, BOOL *rollback) {    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:1]];    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:2]];    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:3]];    if (whoopsSomethingWrongHappened) {        *rollback = YES;        return;    }    // etc…    [db executeUpdate:@"INSERT INTO myTable VALUES (?)", [NSNumber numberWithInt:4]];}];

Documentation

I wouldn't try to do the second update if the first failed.

bool ret = false;[fmdb beginTransaction];ret = [fmdb executeUpdate:@"query1"];if (ret){    ret = [fmdb executeUpdate:@"query2"];    if (!ret)    {         // report error 2    }}if(ret) {    if (![fmdb commit])    {        // panic!    }}else{    if (![fmdb rollback])    {        // panic!    }}

For paranoid robustness you should have a try ... catch block in case anything throws an exception. If you do, you can use it to your advantage.

[fmdb beginTransaction];@try{    if (![fmdb executeUpdate:@"query1"])    {        // report error        @throw someExcpetion;    }    if (![fmdb executeUpdate:@"query2"])    {        // report error        @throw someExcpetion;    }    [fmdb commit]}@catch(NSException* e){    [fmdb rollback];    // rethrow if not one of the two exceptions above}

Swift way:

let queue = FMDatabaseQueue(path: databaseURL.path!)queue.inTransaction() {    db, rollback in    result = db.executeUpdate("INSERT INTO client VALUES (NULL, ?)", client.name ?? "")    if result {        client.ID = Int(db.lastInsertRowId())    } else {        rollback.initialize(true)        print("\(__FUNCTION__) insert into table failed: \(db.lastErrorMessage())")    }}queue.close()