I would like to use regular expression to find and replace the string. In my scenario {3} and {2} are UITextField tag values. Based on the tag value, I would like to replace the respective textfield values and calculate the string value using NSExpression.
Sample Input String :
NSString *cumputedValue = @"{3}*0.42/({2}/100)^2";
Note: The textFields are created dynamically based on JSON response.
I got the answer for this question. Here the computedString contains the value as "{3}*0.42/({2}/100)^2".
- (NSString *)autoCalculationField: (NSString *)computedString {
NSString *computedStringFormula = [NSString stringWithFormat:@"%@",computedString];
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"\\{(\\d+)\\}"
options:0
error:nil];
NSArray *matches = [regex matchesInString:computedStringFormula
options:0
range:NSMakeRange(0, computedStringFormula.length)];
NSString *expressionStr = computedStringFormula;
for (NSTextCheckingResult *r in matches)
{
NSRange numberRange = [r rangeAtIndex:1];
NSString *newString = [NSString stringWithFormat:@"%.2f",[self getInputFieldValue:[computedStringFormula substringWithRange:numberRange]]];
expressionStr = [expressionStr stringByReplacingOccurrencesOfString:[NSString stringWithFormat:@"{%@}",[computedStringFormula substringWithRange:numberRange]] withString:newString];
}
NSExpression *expression = [NSExpression expressionWithFormat:expressionStr];
return [expression expressionValueWithObject:nil context:nil];
}
- (float)getInputFieldValue: (NSString *)tagValue {
UITextField *tempTextFd = (UITextField *)[self.view viewWithTag:[tagValue intValue]];
return [tempTextFd.text floatValue];
}
You could save the textField tags in a NSDictionary with the value that they represent.
After that use stringByReplacingOccurrencesOfString to replace the values that you wish to.
Something like this:
for (NSString *key in dict) {
cumputedValue = [cumputedValue stringByReplacingOccurrencesOfString:[NSString stringWithFormat:@"{@%}", key] withString:[NSString stringWithFormat:@"%@", dict objectForKey:@key]];
}
This way you can have the values replaced
