针对多个keyPath执行valueForKeyPaths

Question

Let's say I have an object with some number of properties and I load up 1000s of these objects into an array. Next, I perform a series of valueForKeyPaths against these properties:

result.property1 = [array valueForKeyPath:@"@sum.property1"];
result.property2 = [array valueForKeyPath:@"@sum.property2"];
result.property3 = [array valueForKeyPath:@"@sum.property3"];
etc...

Summing these properties individually seems pretty inefficient. Is there a better way besides fast enumerating over the properties and summing them manually? ie

for(Foo* foo in array) {
    result.property1 += foo.property1;
    result.property2 += foo.property2;
    result.property3 += foo.property3;
}

Answer 1

KVC requires keys to be strings:

A key is a string that identifies a specific property of an object. Typically, a key corresponds to the name of an accessor method or instance variable in the receiving object. Keys must use ASCII encoding, begin with a lowercase letter, and may not contain whitespace.

So the answer as far as I know is unfortunately you can't do this with valueForKeyPath: you would have to manually do it or enumerate over it.