Convert String to Float to move UISlider - ios

Question

How I can convert time of my JSON data to float value. Below code is written to convert time to float and I passed it to UISlider as total length of audio. I want to move slider with that time spans
//Json Data
{
duration = "00:03:45";
id = 8;
}
//Audio player sider bar function
if(audioController.playbackState == MPMusicPlaybackStatePlaying){
if (isSelected == YES) {
currentAutio = audioList[selectedAudio];
} else {
currentAutio = audioList[0];
}
NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init];
numberFormatter.numberStyle = NSNumberFormatterDecimalStyle;
float value = [numberFormatter numberFromString:currentAutio.duration].floatValue;
float currentPlaybackTime = [audioController currentPlaybackTime];
float TotalLength = value;
float remainingPlaybackTime = TotalLength - currentPlaybackTime;
float sliderPosition = (currentPlaybackTime *100) / TotalLength;
NSLog(#"current playbacktime %f",currentPlaybackTime);
NSLog(#"TotalLength %f",TotalLength);
NSLog(#"remainingPlaybackTime %f",remainingPlaybackTime);
NSLog(#"sliderPosition %f",sliderPosition);
//Update slider
[progressSlider setValue:sliderPosition];
//Update labels
NSDate* d1 = [NSDate dateWithTimeIntervalSince1970:currentPlaybackTime];
NSDate* d2 = [NSDate dateWithTimeIntervalSince1970:remainingPlaybackTime];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"mm:ss"];
NSString *currentTime = [dateFormatter stringFromDate:d1];
NSString *ramainingTime = [dateFormatter stringFromDate:d2];
[trackCurrentPlaybackTimeLabel setText:currentTime];
[trackLengthLabel setText:[NSString stringWithFormat:#"-%#",ramainingTime]];
}
I am getting following output:
Value = 0.00000

Answer 1

I don't think there is a built-in mechanism for converting a time interval into a float, but it's trivially easy to write:
func timeIntervalFrom(_ timeString: String) -> TimeInterval? {
//Add code to validate that string is in correct format
let components = time.components(separatedBy: ":")
guard components.count == 3,
let hours = Double(components[0]),
let minutes = Double(components[1]),
let seconds = Double(components[2]) else {
return nil
}
return hours * 3600 + minutes * 60 + seconds
}

Answer 2

Just convert the duration from String to integer components.
Then calculate the total duration in seconds.
You can get the integer components simply like this:
Swift
let timeComponents = duration.components(separatedBy: ":")
Objective C
NSArray *timeComponents = [duration componentsSeparatedByString:#":"];
timeComponents[0] will be the hours part.
timeComponents[1] will be the minutes part.
timeComponents[2] will be the seconds part.
Total seconds: (hours * 60 * 60) + (minutes * 60) + seconds.
After that, adjusting the slide bar value will be easy :)