Creating NSPredicate based on SQL IN() function for Core Data

core-data, ios, iphone, objective-c

Solution

There is a similar feature in `NSPredicate` as well

NSArray *skus = @[];
NSPredicate *predicate = [NSPredicate 
                              predicateWithFormat:@"AudioSKU IN %@",skus];

And also you cannot treat the predicate strings like usual strings. You cannot form an array of strings and use them for filtering. If there are multiple joins use the `NSCompoundPredicate`.

A good reference Using NSPredicate to filter Data

Problem

I have a scenario where I must fetch multiple records from Core Data based on multiple values of a given column. A common SQL query for this purpose would be ``` SELECT * FROM suppliers WHERE supplier_name in ('IBM', 'Hewlett Packard', 'Microsoft'); ``` I have not been able to figure out how I'd use the native `IN()` function for this purpose. The way I am creating the `NSPredicate` at the moment seems redundant and is as follows. ``` NSMutableArray *predicateArray = [NSMutableArray array]; [skus enumerateObjectsUsingBlock:^(NSString *sku, NSUInteger idx, BOOL *stop) { [predicateArray addObject: [NSString stringWithFormat:@"(AudioSKU == \"%@\")", sku]]; }]; NSString *predicateString = [predicateArray componentsJoinedByString:@" OR "]; NSPredicate *predicate = [NSPredicate predicateWithFormat:predicateString]; ``` Is there a proper way to use NSPredciate or NSExpression for using `IN` function of SQL? Please enlighten me.

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