Here it is an other big problem while porting applications from C language to objective C for the iPhone.
NSString *myString = @"12.34";
float stringFloat = [myString floatValue];
Alike you can convert NSString to double
NSString *myString = @"12.34";
double stringFloat = [myString doubleValue];
And viceversa you can use:
float myFloat = 0.1234;
NSString *myString = [NSString stringWithFormat:@"%f", myFloat];
gg1