How to catch a Nan?
NaN is not equal to any value, including NaN, use this property instead of the equal-to operator (==) or not-equal-to operator (!=) to test whether a value is or is not NaN.
Nan represents Not a number
When it happens to get a Nan as a result of an expression you have to find a way to catch it before.
Let’s think an if statement and inside this the appropriate check.
A working code is the following:
Objective-C
The class property [NSDecimalNumber notANumber] is just for this purpose. In some languages NaN != NaN
if NSNumber is a NaN, convert it to a double and use the C function isnan():
NSNumber *validNumber = [NSNumber numberWithDouble: 1.];
NSLog( @"%d", isnan(validNumber.doubleValue) ); // prints "0"
NSNumber *nanNumber = [NSNumber numberWithDouble: 0./0.];
NSLog( @"%d", isnan(nanNumber.doubleValue) ); // prints "1"
[[NSDecimalNumber notANumber] isEqualToNumber:myNumber]
if ([[NSDecimalNumber decimalNumberWithString:self.price...] isEqual:[NSDecimalNumber notANumber]]) {
//Code
}
SWIFT
let x = 0.0
let y = x * .infinity
// y is a NaN
// Comparing with the equal-to operator never returns 'true'
print(x == Double.nan)
// Prints "false"
print(y == Double.nan)
// Prints "false"
// Test with the 'isNaN' property instead
print(x.isNaN)
// Prints "false"
print(y.isNaN)
// Prints "true"