Prevent Users from Entering Multiple Decimals In Objective-C

Question

I am making an only number input app (still) in which users press a button, I store a value into a string to display in a label.

Works great for the most part, except I cannot figure out how to prevent users from entering more than one decimal in a single string. .

I looked at this Stack overflow question, but trying to amend the code for my own just resulted in a whole bunch of errors. Does anyone have any advice?

- (void)numberBtn:(UIButton *)sender {
    if (self.sales.text.length < 10) {
        if(self.sales.text.length != 0){
            NSString *lastChar = [self.sales.text substringFromIndex:[self.sales.text length] - 1];
            
            if([lastChar isEqualToString:@"."] && [sender.titleLabel.text isEqualToString:@"."] && [sender.titleLabel.text stringByAppendingString:@"."]){
                return;   
            }
            
            if ([lastChar isEqualToString:@""] && [sender.titleLabel.text isEqualToString:@""]){
                self.numbers = @"0.";
            }
            if ([self.sales.text rangeOfString:@"."].length > 0) {
                NSArray *array = [self.sales.text componentsSeparatedByString:@"."];
                if (array.count == 2) {
                    NSString *decimal = array.lastObject;
                    if (decimal.length > 2) {
                        return;
                    }
                }
            }
        }
        
        self.numbers = [NSString stringWithFormat:@"%@%@",self.numbers,sender.titleLabel.text];
        self.sales.text = self.numbers;
    }
}

Answer 1

Two steps...

• Check to see if the button is a decimal .
• if yes, see if the current label text already contains a .

If it does, return. If not, continue processing your button input:

- (void)numberBtn:(UIButton *)sender {
    NSString *btnTitle = sender.currentTitle;
    NSString *curText = self.sales.text;
    if ([btnTitle isEqualToString:@"."]) {
        if ([curText containsString:@"."]) {
            NSLog(@"%@ : Already has a decimal point!", curText);
            return;
        }
    }
    // whatever else you want to do with the input...
}