Count number of times object appears in NSArray - ios

Question

I have an NSArray of 5 dice (dice1, dice2, dice3...). Once I have run the random number generator each dice1, dice2, dice3... can return a value between 1-6.
I would like to be able to count how many times a value of 1-6 has been returned.
I'm not too sure of the best way, whether I should turn the int number 1-6 into a string to match.

Answer 1

This is one of those situations where I don't feel that there is a particularly elegant solution due to the inability of Foundation types (such as NSCountedSet) to store intrinsic types (such as int). Swift's automatic boxing/unboxing of ints into NSNumber is a nice feature in this sort of situation.
Since you dealing with a small number of dice and a small number of possible values then you could ignore objects, sets and all that and just loop over your dice array, updating an array of integer counts.
The other, more complex, but object-oriented approach is to create a Die class:
Die.h
#import <Foundation/Foundation.h>
#interface Die : NSObject
-(instancetype)initWithSides:(NSUInteger)sides;
-(instancetype)initWithSides:(NSUInteger)sides initialValue:(NSUInteger)value;
-(NSUInteger)value;
-(NSUInteger)roll;
-(NSUInteger)sides;
#end
Die.m
#import "Die.h"
#interface Die ()
#property NSUInteger currentValue;
#property NSUInteger numberOfsides;
#end
#implementation Die
- (instancetype)initWithSides:(NSUInteger)sides {
NSAssert(sides>1, #"Dice must have at least 2 sides");
if (self = [super init]) {
self.numberOfsides = sides;
[self roll];
}
return self;
}
- (instancetype)initWithSides:(NSUInteger)sides initialValue:(NSUInteger)value {
NSAssert(sides>1, #"Dice must have at least 2 sides");
NSAssert(value <= sides, #"Initial value must not exceed number of sides");
if (self = [super init]) {
self.numberOfsides = sides;
self.currentValue = value;
}
return self;
}
- (NSUInteger)roll {
self.currentValue = arc4random_uniform((UInt32)self.numberOfsides)+1;
return self.currentValue;
}
- (NSUInteger)value {
return self.currentValue;
}
- (NSUInteger)sides {
return self.numberOfsides;
}
- (NSUInteger)hash {
return self.currentValue;
}
- (BOOL)isEqual:(id)object {
if (self == object) {
return YES;
}
if (![object isKindOfClass:[Die class]]) {
return NO;
}
return [self isEqualToDie:(Die *)object];
}
- (BOOL) isEqualToDie:(Die *)otherDie {
return self.currentValue == otherDie.value;
}
#end
So now you have an object that can be stored in an NSCountedSet and you can retrieve the counts. This bit is slightly awkward since you need to compare to a Die with the appropriate value, not just the value itself:
// self.dice is an array of `Die` objects
NSCountedSet *valueCounts = [NSCountedSet setWithArray:self.dice];
for (int i=1;i<7;i++) {
NSUInteger count = [valueCounts countForObject:[[Die alloc] initWithSides:6 initialValue:i]];
NSLog(#"There are %lu dice showing %d",count,i);
}

Answer 2

use dictionaries :
let arrNum = [“one”, “two”, “three”, “two”]
var countNumber:[String:Int] = [:]
for item in arrNum {
countNumber[item] = (countNumber[item] ?? 0) + 1
}
for (key, value) in countNumber {
print("\(key) occurs \(value) time")
}
o/p :
one occurs 1 time
two occurs 2 time
three occurs 1 time