Multiple conditions in NSPredicate - objective-c

Question

How to use multiple conditions with NSPredicate?
I am using this but not getting anything in the returned array .
NSPredicate *placePredicate = [NSPredicate predicateWithFormat:#"place CONTAINS[cd] %# AND category CONTAINS[cd] %# AND ((dates >= %#) AND (dates <= %#)) AND ((amount >= %f) AND (amount <= %f))",placeTextField.text,selectedCategory,selectedFromDate,selectedToDate,[amountFromTextField.text floatValue],[amountToTextField.text floatValue]];
NSArray *placePredicateArray = [dataArray filteredArrayUsingPredicate:placePredicate];
NSLog(#"placePredicateArray %#", placePredicateArray);
The amount and the category can be empty sometimes. How should I construct the NSPredicate?

Answer 1

You can build your placesPredicate using other NSPredicate objects and the NSCompoundPredicate class
Something like :
NSPredicate *p1 = [NSPredicate predicateWithFormat:#"place CONTAINS[cd] %#", placeTextField.text];
NSPredicate *p2 = [NSPredicate predicateWithFormat:#"category CONTAINS[cd] %#", selectedCategory];
NSPredicate *p3 = [NSPredicate predicateWithFormat:#"(dates >= %#) AND (dates <= %#)", selectedFromDate,selectedToDate];
NSPredicate *p4 = [NSPredicate predicateWithFormat:#"(amount >= %f) AND (amount <= %f)", [amountFromTextField.text floatValue],[amountToTextField.text floatValue]];
NSPredicate *placesPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:#[p1, p2, p3, p4]];
Now, if you are missing category for example you can just use a dummy YES predicate to replace it :
NSPredicate *p2;
if (selectedCategory) {
p2 = [NSPredicate predicateWithFormat:#"category CONTAINS[cd] %#", selectedCategory];
} else {
p2 = [NSPredicate predicateWithBool:YES]
}

Answer 2

I would tend to handle this one piecemeal. That is,
placePredicate = [NSPredicate predicateWithFormat:#"place CONTAINS[cd] %#",placeTextField.text];
NSMutableArray *compoundPredicateArray = [ NSMutableArray arrayWithObject: placePredicate ];
if( selectedCategory != nil ) // or however you need to test for an empty category
{
categoryPredicate = [NSPredicate predicateWithFormat:#"category CONTAINS[cd] %#",selectedCategory];
[ compoundPredicateArray addObject: categoryPredicate ];
}
// and similarly for the other elements.
Note that I don't bother even putting into the array the predicate for category (or anything else) when I know there isn't one.
// Then
NSPredicate *predicate = [NSCompoundPredicate andPredicateWithSubpredicates:
compoundPredicateArray ];
And if I were planning to do it a lot, I wouldn't use the format method, but keep around the building blocks and just change whatever changes between uses.

Answer 3

Suppose a class Person with attributes "name", "age", "income"
"personArray" is array of class Person
NSPredicate *mypredicate = [NSPredicate predicateWithBlock:^BOOL(personObj Person, NSDictionary *bindings) {
NSNumber *age = personObj.age;
String *name = personObj.name;
NSNumber *income = personObj.income
BOOL result = (age > 20 && name == "Stack" && income >40000);
return result;
}];
NSArray *filteredArray = [personArray filteredArrayUsingPredicate: mypredicate];
For further you can read this article Array Filter Using Blocks
In Swift
let filterArray = personArray.filter
{ person in
let age = personObj.age;
let name = personObj.name;
let income = personObj.income
BOOL result = (age > 20 && name == "Stack" && income >40000);
return result;
}