Unable to bridge NSNumber to Float in JSON parsing

Question

Get this error:

Fatal error: Unable to bridge NSNumber to Float. What is the problem?

This is the original message, it is float and not string.

{\"name\":\"Tomas\",\"gender\":\"male\",\"probability\":0.99,\"count\":594}

Answer 1

You have many different types of numbers in Swift/Foundation. Your NSKeyValueCoding has been set as instance of NSNumber (see excerpt of JSON serialization documentation below) so you need to read as is, and then ask to convert this NSNumber as Float if needed:

if let n = d.value(forKey: "probability") as? NSNumber {
    let f = n.floatValue
}

JSONSerialization documentation says:

A Foundation object that may be converted to JSON must have the following properties:

• The top level object is an NSArray or NSDictionary.
• All objects are instances of NSString, NSNumber, NSArray, NSDictionary, or NSNull.
• All dictionary keys are instances of NSString.
• Numbers are not NaN or infinity.