Why does my NSNumberFormatter object print “2” for input 1.0?

Question

That looks like a bug in the API:

When my input CGFloat is 0.0, I get this:

Input = 0.000000, Output = +0

When my input CGFloat is 1.0, I get this:

Input = 1.000000, Output = +2

Obviously that's not what I want ;-)

Now here is how I create that NSNumberFormatter object:

    NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
    [formatter setAlwaysShowsDecimalSeparator:NO];
    [formatter setAllowsFloats:YES];
    [formatter setFormatterBehavior:NSNumberFormatterBehavior10_4];
    [formatter setMinimumFractionDigits:0];
    [formatter setPlusSign:@"+"];
    [formatter setMinusSign:@"-"];
    [formatter setPositivePrefix:@"+"];
    [formatter setNegativePrefix:@"-"];
    [formatter setRoundingMode:NSNumberFormatterRoundUp];

and this is how I let it format my CGFloat of 1.0f:

CGFloat myValue = 1.0f;     
NSNumber *number = [NSNumber numberWithFloat:myValue];
NSLog(@"Input = %f, Output = %@", myValue, [self.inputValueFormatter stringFromNumber:number]);

May be the roundingMode the problem here? Which should I specify? Or is there another cause for this strange behavior?

Answer 1

Adding this seems to do the trick for me, although I'm not sure why it does:

[formatter setRoundingIncrement: [NSNumber numberWithFloat: 1]];