I currently loaded "car" objects from an SQL file using the tutorial from dBlog. Now that I have all of my car objects loaded into an NSMutable array. I wish to make a method to return a specific object from the NSMutable array based on two criteria. The first criteria is the type of the vehicle, and the other being the year of the vehicle which are the properties of the object.
I know that you can return an object based on index, but this would be too confusing.
How would I be able to return a specific object based on these criteria?
Note: the objects in the NSMutable array will not have the same vehicle type and year. However there are several vehicles of the same type, and several vehicles of the same year.
Just search the indicies for the name of the car and the year of the model.
You can use a collection for loop(dont know if its the right term but its what i call them) and then just search if both the model and the year are equal to the search terms.
Code:
int index = 0;
int foundAtIndex;
for(CarModel *car in carArray){//this will search every index
if([car.model isEqualToString:@"Model"] && car.year = yearSearchedFor){
foundAtIndex = index;
break;
}
else
index++;
}
I currently loaded "car" objects from an SQL file using the tutorial from dBlog. Now that I have all of my car objects loaded into an NSMutable array. I wish to make a method to return a specific object from the NSMutable array based on two criteria. The first criteria is the type of the vehicle, and the other being the year of the vehicle which are the properties of the object.
I know that you can return an object based on index, but this would be too confusing.
How would I be able to return a specific object based on these criteria?
Note: the objects in the NSMutable array will not have the same vehicle type and year. However there are several vehicles of the same type, and several vehicles of the same year.
Thanks for your help.
This is a bad way to use SQL. You are forcing the system to load all your car objects from disk into memory, and then do brute-force string compares on all the types. You will maximize the amount of memory required, AND end up with a very slow search, since the app will always need to read all of your records into memory. On a memory-starved iOS device that will fail for a moderately large table.
You should set up type and year to be keys in your table, and then use an SQL select statement to find the objects that matches your criteria. That way SQL can use a hash function to find the keys, without loading any of the records into memory.
I haven't used SQL directly from iOS yet, so I can't give you the specifics. I've used Core Data, which offers some very useful features on top of SQL.
Check out this password generator app that shows various techniques including using a data container singleton object to share data between objects in your project.
This is a bad way to use SQL. You are forcing the system to load all your car objects from disk into memory, and then do brute-force string compares on all the types. You will maximize the amount of memory required, AND end up with a very slow search, since the app will always need to read all of your records into memory. On a memory-starved iOS device that will fail for a moderately large table.
You should set up type and year to be keys in your table, and then use an SQL select statement to find the objects that matches your criteria. That way SQL can use a hash function to find the keys, without loading any of the records into memory.
I haven't used SQL directly from iOS yet, so I can't give you the specifics. I've used Core Data, which offers some very useful features on top of SQL.
What you are saying makes perfect sense. However, I'm new to SQL and fairly new to obj c so I've been trying to find tutorials/readings on how to read data from an SQL database. The only two tutorials that I have found first put the data in an NSMutablearray and then loaded the data onto a table view by going through all of the objects in the NSMutablearray. I am not trying to put the data into a table view. I'm simply trying to display the properties of a car in labels.
I do want to do it your way, but i'm not sure how to set up the year and type as keys or how to use a hash function for SQL. I've been looking around for readings but I don't seem to find any. I'm trying to use the year and type to find the specific car and all the data that comes along with it such as wheel size, engine size, number of pistons etc. I'm trying to make it as easy as label.text = Car.engineSize, label2.text = Car.pisons.....
Are there any readings, articles or tutorials you know of that can allow me to do read SQL data more efficiently?
NSMutable Array Search Problem
Linear Mode
