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Posts from the ‘Objective C Noise’ Category

21
Oct

Work With Numbers in Objective C (NSNumber and NSDigitalNumber)

Next example shows you how to work with NSNumber and NSDecimalNumer objects in Objective C. First part show you standard use, second part shows how to work with NSNumer objects in simplified form and last part shows how to work with NSDecimalNumber objects.

In this example we define two NSNumber numbers and then we add them (or we muliply them).

NSNumber *a, *b, *c;
a = [NSNumber numberWithInt:10];
b = [NSNumber numberWithInt:20];
c = [NSNumber numberWithInt:([a intValue] + [b intValue])];
 
// short notations
a = @10;
b = @20;
c = @([a integerValue] * [b integerValue]);
 
// using NSDecimalNumbers
NSDecimalNumber *a1, *a2, *a3;
a1 = [[NSDecimalNumber alloc] initWithInt:15];
a2 = [[NSDecimalNumber alloc] initWithInt:30];
a3 = [a1 decimalNumberByMultiplyingBy:a2];
 
// define a boolean number
NSNumber *isItTrue = @YES;
 
// convert string to int
int val1 = [@"100" intValue];
NSNumber *d = [NSNumber numberWithInt:val1];
 
NSLog(@"\n isItTrue = %@ | d = %@", isItTrue, d);

You can also learn how to convert a NSString to a NSNumber object.

Working with NSNumbers to make computations is slow. Better use C type numbers instead. But anyway just in case you need this, it might be useful to know how to use NSNumber object to make mathematical operations.

26
Jan

Renaming a Getter in Objective C When Using @property

If we use @property to define setters and getters for our class variables if we want our getter name to be different (by default if we do not rename it, our getter have the same name as the variable name) we will use the following syntax:

@property (strong, nonatomic, getter=showJustAString) NSString *justAString

That way our getter will be showJustAString.

Note that by default when we define the property using:

@property (strong, nonatomic) NSString *justAString

our getter will be justAString.