Surprising replacingOccurrences Results for Unicode-Unaware Developers

[FlorianPircher]

The contains method changing behavior when importing Foundation is also surprising and good to be aware of:

NSString.contains(_:) returns false for empty string argument

This depends on whether Foundation is imported. We have: "foo".contains("") // ⟹ true but import Foundation "foo".contains("") // ⟹ false This is not expected.