創建一個Fraction類（分數）實現分數的加減乘除，比較大小、約分等方法.要求：爲類添加屬性

<span style="font-family:KaiTi_GB2312;font-size:32px;">#import <Foundation/Foundation.h>
@interface Fraction : NSObject
@property (nonatomic) NSInteger molecular;       //分子
@property (nonatomic) NSInteger denominator;   //分母
//初始化
- (id)initWithMolecular:(NSInteger)molecular denominator:(NSInteger)denominator;
//分數相加
- (Fraction *)sumFraction:(Fraction *)fraction;
//分數相減
- (Fraction *)differencingFraction:(Fraction *)fraction;
//分數相乘
- (Fraction *)multiplicaFraction:(Fraction *)fraction;
//分數相除
- (Fraction *)divisionFraction:(Fraction *)fraction;
//約分
- (Fraction *)reduceOfFraction;
//比較大小
- (void)compareFraction:(Fraction *)fraction;
@end
</span>

<span style="font-family:KaiTi_GB2312;font-size:32px;">@implementation Fraction
- (id)initWithMolecular:(NSInteger)molecular denominator:(NSInteger)denominator
{
    self = [super init];
    if (self) {
        _molecular = molecular;
        _denominator = denominator;
    }
    return self;
}
//分數相加
- (Fraction *)sumFraction:(Fraction *)fraction
{
    Fraction *temp = [Fraction alloc];
    temp.molecular = self.molecular * fraction.denominator + self.denominator * fraction.molecular;
    temp.denominator = self.denominator * fraction.denominator;
    return temp;
}
//分數相減
- (Fraction *)differencingFraction:(Fraction *)fraction
{
    Fraction *temp = [Fraction alloc];
    temp.molecular = _molecular * fraction.denominator - _denominator * fraction.molecular;
    temp.denominator = _denominator * fraction.denominator;
    return temp;
}
//分數相乘
- (Fraction *)multiplicaFraction:(Fraction *)fraction
{
    Fraction *temp = [Fraction alloc];
    temp.molecular = _molecular * fraction.molecular;
    temp.denominator = _denominator * fraction.denominator;
    return temp;
}
//分數相除
- (Fraction *)divisionFraction:(Fraction *)fraction
{
    Fraction *temp = [Fraction alloc];
    temp.molecular = self.molecular * fraction.denominator;
    temp.denominator = self.denominator * fraction.molecular;
    return temp;
}
//比較大小
- (void)compareFraction:(Fraction *)fraction
{
    Fraction *temp = [Fraction alloc];
    temp = [self differencingFraction:fraction];
    if (temp.molecular > 0) {
        NSLog(@"%ld/%ld較大",self.molecular,self.denominator);
    }else if(temp.molecular == 0){
        NSLog(@"兩個數一樣大");
    }else{
        NSLog(@"%ld/%ld較大",fraction.molecular,fraction.denominator);
    }
}
//約分
- (Fraction *)reduceOfFraction
{
    if (self.molecular < self.denominator) {
        for (NSInteger i = self.molecular; i > 0; i--) {
            if (self.molecular % i == 0 && self.denominator % i == 0) {
                self.molecular = self.molecular / i;
                self.denominator = self.denominator / i;
            }
        }
    }else if(self.molecular > self.denominator){
        for (NSInteger i = self.denominator; i > 0; i--) {
            if (self.molecular % i == 0 && self.denominator % i == 0) {
                self.molecular = self.molecular / i;
                self.denominator = self.denominator / i;
            }
        }
    }
    return self;
}

@end</span>

<span style="font-family:KaiTi_GB2312;font-size:32px;"> @autoreleasepool {
        Fraction *fra1 = [[Fraction alloc]initWithMolecular:3 denominator:4];
        Fraction *fra2 = [[Fraction alloc]initWithMolecular:2 denominator:5];
        //分數相加
        Fraction *number1 =[fra1 sumFraction:fra2];
        [number1 reduceOfFraction];
        NSLog(@"%ld/%ld ",(long)number1.molecular,number1.denominator);
        
        //分數相減
        Fraction *number2 =[fra1 differencingFraction:fra2];
        [number2 reduceOfFraction];
        NSLog(@"%ld/%ld",number2.molecular,number2.denominator);
        
        //分數相乘
        Fraction *number3 = [fra1 multiplicaFraction:fra2];
        [number3 reduceOfFraction];
        NSLog(@"%ld/%ld",number3.molecular,number3.denominator);
        
        //分數相除
        Fraction *number4 = [fra1 divisionFraction:fra2];
        [number4 reduceOfFraction];
        NSLog(@"%ld/%ld",number4.molecular,number4.denominator);
        
        //比較大小
        [fra1 compareFraction:fra2];</span>