Keyboard Unresponsive/Laggy During Heavy Logic

Hey guys! So I was hoping someone could help me with this little programming issue I've been having. Basically I'm developing an iPhone app to convert various base numbers between one another (binary to octal, for example). I have it set up with multiple text fields, with each field representing a different base system. The user can input into any of these text fields, and the input's converted value will be reflected to the appropriate other text field (for example, if the user typed in 101 in the binary field, the octal field would read 5. Everything works fine, until I get into higher numbers. See, I have it set up so the numbers will convert live as the user types, and due to the heavy amount of string manipulation I have going, it begins to slow the app down as the input number gets longer. And as a result, the keyboard input becomes laggy - especially on older devices - freezing up during the execution of the number conversion code, then becoming fully responsive.

This is kind of an issue, as if a user inputs a large number, it could take a very long time for them to input the whole thing, between typing and waiting for the keyboard to become responsive. Therefore, I wanted to know if there is any way around this? Maybe something which would give priority to the keyboard above everything else? I saw this other app that converts length values in the same UI way that mine does, though in this app, when the numbers get large, the updating of the text fields does slow down, but the keyboard input never gets laggy! It's as if the keyboard is living in its own world, unaffected by whatever other logic is going on in the background.

Please, if anyone knows anything about this, please give me a hand. As always, any help is always appreciated!

 

Thanks for the replies! Here's my code, since you asked:

Code:

- (NSMutableString *)binaryToOctal:(NSMutableString *)input{
    NSMutableString *inputString = input;                                   // input string from text field
    int numberOfChars = [inputString length];                               // number of characters from inputString. used to check to see if input is empty as well as if additional 0's are needed
    NSMutableString *finalString = [NSMutableString stringWithString:@""];  // will hold the final formatted octal string
    
    if (numberOfChars != 0) {                                               // if there is no string in the input text field, don't do anything! (will crash otherwise)
        
        NSLog(@"numberOfChars: %i", numberOfChars);
        
                                                                            // % is modulus; it divides numberOfChars by 3, then takes the remainder as the result
        if (numberOfChars % 3 != 0) {                                       // run test to see if we need to add a 0 to the left side of the inputString
            NSLog(@"Invalid string, must append 0(s) to left side");
            [inputString insertString:@"0" atIndex:0];
            NSLog(@"New String: %@", inputString);
        }
        
        numberOfChars = [inputString length];                               // refresh the inputString length, since it may have changed from the above test
        if (numberOfChars % 3 != 0) {                                       // run the test again, in case we need two 0's at the left side
            NSLog(@"Invalid string, must append 0(s) to left side");
            [inputString insertString:@"0" atIndex:0];
            NSLog(@"New String: %@", inputString);
        }
        
        int currentPower = 0;                                               // will track the current power, used below
        
        do {
            NSMutableString *currentSet = [NSMutableString stringWithString:[inputString substringFromIndex:[inputString length]-3]];   // takes set of 3 numbers from right side of inputString
            NSLog(@"currentSet: %@", currentSet);
            inputString = [NSMutableString stringWithString:[inputString substringToIndex:[inputString length]-3]];                     // removes set of 3 numbers from right side of inputString by re-creating inputString minus the 3 numbers on the right
            int totalFromCurrentSet = 0;                                                                                    // total converted octal value from currentSet
            
            do {
                NSString *currentNumber = [currentSet substringFromIndex:[currentSet length]-1];                            // takes first number from right side of currentSet
                NSLog(@"currentNumber (from currentNumber variable): %@", currentNumber);
                if ([currentNumber isEqualToString:@"1"]) {                                                                 // if currentNumber is 1
                    NSLog(@"currentNumber detected by if statement as 1");
                    int x = pow(2, currentPower);                                                                           // 2^currentPower
                    NSLog(@"x: %i", x);
                    totalFromCurrentSet += x;                                                                               // adds 2^currentPower to totalFromCurrentSet
                    NSLog(@"new totalFromCurrentSet: %i", totalFromCurrentSet);
                    currentPower += 1;                                                                                      // incremenets the currentPower, for the next number
                    NSLog(@"new currentPower: %i", currentPower);
                    currentSet = [NSMutableString stringWithString:[currentSet substringToIndex:[currentSet length]-1]];    // remove number on right side of currentSet by re-creating currentSet minus the number on the right
                    NSLog(@"new currentSet: %@", currentSet);
                }
                if ([currentNumber isEqualToString:@"0"]) {
                    NSLog(@"currentNumber detected by if statement as 0");
                    currentPower += 1;                                                                                      // incremenets the currentPower, for the next number
                    NSLog(@"currentPower: %i", currentPower);
                    currentSet = [NSMutableString stringWithString:[currentSet substringToIndex:[currentSet length]-1]];    // remove number on right side of currentSet by re-creating currentSet minus the number on the right
                    NSLog(@"new currentSet: %@", currentSet);
                }
            } while ([currentSet length] != 0);     // only do the above while there are still numbers in the current set
            
            currentPower = 0;                       // reset the currentPower, so it doesn't get too big for the next set of numbers
            NSMutableString *totalFromCurrentSetString = [NSMutableString stringWithFormat: @"%i", totalFromCurrentSet];    // totalFromCurrentSet, created as a string
            NSLog(@"totalFromCurrentSetString: %@", totalFromCurrentSetString);
            [finalString insertString:totalFromCurrentSetString atIndex:0];                                                 // inserts totalFromCurrentSetString to the right side of finalString
            
        } while ([inputString length] != 0);        // only do the above while there are still numbers in the input string
        
        NSLog(@"finalString: %@", finalString);
    }
    
    
    
    return finalString;     // returns the final formatted octal string
}

Like the name implies, this method converts a binary input string into an octal string, then returns it. I think I agree with everybody in that it should be very fast, since all I'm doing is some string manipulation. I'm only a beginner/intermediate Obj-C programmer, so if something inefficient is going on, I probably don't know about it. At first I thought it might be because of memory leaks or something, but I ran the app through Instruments and got no leaks, even while processing the heavy numbers. Let me know if you guys see something. Thanks!

Also thanks jonnymo5. I didn't really want to get into multithreading on this app, but Grand Central sounds like a great last resort.

 

Thank you all so much for your help. robbieduncan, I tried your suggestion of minimizing object creation by putting my NSString and NSMutableString creations on the outside of my loop, and that didn't help much. Then I tried chown33's suggestion on NSLogs, and now the program SCREAMS!!! Tested on an iPhone 4S and an iPhone 3G. The 4S is obviously faster than the 3G, but the 3G would become unresponsive at times with all those NSLogs in there. It never occurred to me that NSLogs could slow a program down, but now I know!

chown33, I will also learn to better utilize the debugger. If it can do like you said and step through an analyze each variable, then it seems like a great alternative to NSLog. It seems like NSLog is ok for a quick debugger-less solution, but shouldn't be in the final program.

I'm also going to take everybody's advice by re-writing the method to better utilize ints rather than strings.

Thanks you again! I'd be really stuck without you right now!

PS: Sorry this thread got kinda off-topic - for anybody who came here looking to make the keyboard more responsive, you should give jonnymo5's solution a look.

 

Really sorry to do this, but I have another issue. You guys suggested to convert the input string into an int, then convert that int into another base format. That sounds great, except that ints, as well as every numeric data type of Objective-C that I know of have limits, the limit that my program showing me for int being 2147483647. I'd really love to make this app faster and more optimized, but I just can't limit users to entering less than 10 digits for a binary value. Any ideas?

 

chown33, thanks for your help (again). I understand some of what you're saying, but you're right when you said I should learn how ints and longs and stuff actually represent their numbers. I'll give what you suggested a look. Thanks again!

mobilehaathi, thanks for the post, but I don't think you understand the purpose of my program. The program will convert whatever the user types from binary into whatever (octal, hex, etc.). Therefore, it is entirely possible for a user to enter a string with a length bigger than the number you gave, but still have the program freak out because it is bigger than the max value of an int or long or whatever (again, I don't know much about it). Just thought I'd clarify.