在目标C中赋值后，浮点值始终返回1

Question

I am storing float value in UserDefaults.

[[NSUserDefaults standardUserDefaults] setValue:[NSNumber numberWithFloat:self.labelSlider.lowerValue] forKey:@"KEYSLIDERLOWERVALUE"];
[[NSUserDefaults standardUserDefaults] synchronize];

but when I fetch value in variable "lowerVal", proper value assign to float variable but when I am going to assign float "lowerVal" to self.lableSlider.lowerValue it always give me 1.

float lowerVal = [[[NSUserDefaults standardUserDefaults] valueForKey:@"KEYSLIDERLOWERVALUE"] floatValue];

if (lowerVal > [[self.arrPriceRange valueForKey:@"minPrice"] floatValue]) {
        self.labelSlider.lowerValue = lowerVal;
    }else{
        self.labelSlider.lowerValue = [[self.arrPriceRange valueForKey:@"minPrice"] floatValue];
    }

in short when I print lowerVal in console it gives me 4.55(correct value) but when I print self.lableSlider.lowerValue it gives me 1.

How can I solve this problem?

Answer 1

You can use this code:

Setting Default Values

-(void) saveFloatValue:(float)x forKey:(NSString *)key {
    NSUserDefaults * userDefaults = [NSUserDefaults standardUserDefaults];
    [userDefaults setFloat:x forKey:key];
    [userDefaults synchronize];
}

Getting Default Values

-(float) retrieveFloatValueWithKey:(NSString *)key {
    NSUserDefaults * userDefaults = [NSUserDefaults standardUserDefaults];
    return [userDefaults floatForKey:key];
}

Source: https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSUserDefaults_Class/#//apple_ref/occ/instm/NSUserDefaults/setFloat:forKey:

Answer 2

Are you using NMRangeSlider? I've checked the source code and found:

- (void) setLowerValue:(float)lowerValue
{
    float value = lowerValue;

    if(_stepValueInternal>0)
    {
        value = roundf(value / _stepValueInternal) * _stepValueInternal;
    }

    value = MIN(value, _maximumValue);
    value = MAX(value, _minimumValue);

    if (!isnan(_lowerMaximumValue)) {
        value = MIN(value, _lowerMaximumValue);
    }

    value = MIN(value, _upperValue - _minimumRange);

    _lowerValue = value;

    [self setNeedsLayout];
}

Take care of these lines:

value = MIN(value, _maximumValue);
value = MAX(value, _minimumValue);

The default value of _maximumValue is 1.0, so lowerValue can not exceed it. In this case, you should set maximumValue and minimumValue due to your requirement.

Answer 3

You are using wrong methods to access values in NSUserDefaults . Exchange

• valueForKey: with objectForKey:
• setValue:forKey: with setObject:forKey:

In your case you could also use the specialized methods for floating point types, which do the boxing/unboxing for you:

[[NSUserDefaults standardUserDefaults] setFloat:self.labelSlider.lowerValue forKey:@"KEYSLIDERLOWERVALUE"];

float lowerVal = [[NSUserDefaults standardUserDefaults] floatForKey:@"KEYSLIDERLOWERVALUE"];

As a sidenote: calling synchronize is not necessary and just a waste of resources.

The methods you've been using ( valueForKey: and setValue:forKey: ) are KVC accessors that are not expected or documented to work in NSUserDefaults .