NSUserDefaults with time floats

问题

I'm making a game in which the user must complete a task as quickly as possible, and I would like to display the user's best time and update the best time when he or she achieves a new one. I have:

float BestTimeValue
float starttime
-(void)start{
starttime += 0.001;
timelabel.text = [NSString stringWithFormat:@"%.3f", starttime];
}
if (starttime < BestTimeValue) {
    [[NSUserDefaults standardUserDefaults] setObject:starttime forKey:[@"BestTimeValue"];
}

and in my viewdidload:

BestTimeValue = [[NSUserDefaults standardUserDefaults] objectForKey:@"BestTimeSaved"];

starttime stops when the game is over, but the value won't display in the label. Thanks!

回答1:

You can't use a float with the setObject:forKey: and objectForKey: methods.

Use setFloat:forKey: and floatForKey:.

if (starttime < BestTimeValue) {
    [[NSUserDefaults standardUserDefaults] setFloat:starttime forKey:[@"BestTimeValue"];
}


BestTimeValue = [[NSUserDefaults standardUserDefaults] floatForKey:@"BestTimeSaved"];

回答2:

[[NSUserDefaults standardUserDefaults] setObject: forKey:] As the name says, it only accept object like NSString, NSNumber, NSDictionary, etc.

So you have to use other method [[NSUserDefaults standardUserDefaults] setFloat: forKey] or save the float in a NSNumber to use the setObjet Method [NSNumber numberWithFloat:thefloat];

来源：https://stackoverflow.com/questions/24591241/nsuserdefaults-with-time-floats