删除重复字符

需求:

1、为可变字符串类添加一个检测是不是有重复字母的方法：例如：@“abccd”调用这个函数后变成@”abcd”;

2、给学员定义一个“私有”方法：判断学员是不是有时间。定义一个协议：服务员和学员的协议，服务员给学员送餐。如果学员忙，就让服务员送餐。

---

1:

NSMutableString+RemoveRep.h

#import <Foundation/Foundation.h>

@interface NSMutableString (RemoveRep)
-(void)removeRepeat:(NSString *)aNum;
@end

NSMutableString+RemoveRep.m

#import "NSMutableString+RemoveRep.h"

@implementation NSMutableString (RemoveRep)
-(void)removeRepeat:(NSString *)aNum
{
    NSMutableArray *mArr = [[NSMutableArray alloc]initWithCapacity:10];
    for (int i = 0;i < aNum.length;i++)
    {
        [mArr addObject:[aNum substringWithRange:NSMakeRange(i,1)]];
    }
    [self compareNum:mArr];
    NSLog(@"%@",mArr);
    
}
//比较是否相等
-(NSMutableArray *)compareNum:(NSMutableArray *)mArr//abcbcbcbda
{
    int count = mArr.count;//重新定义了,count不会减一
/*错误,因为冒泡排序只比较两个相邻的数
    for (int j = 0; j < count - 1; j++)
    {
        for (int i = 0; i < count - 1 - j; i++)
        {
            NSString *a = [mArr objectAtIndex:i];
            NSString *b = [mArr objectAtIndex:i+1];
            
            if ([a isEqualToString:b])
            {
                NSLog(@"repeat = %@",[mArr objectAtIndex:i]);
               [mArr removeObjectAtIndex:i];
                count--;//数组长度发生变化
            }
        }
    }
*/
    for (int j = 0; j < count - 1; j++)//百钱买百鸡式的冒泡遍历
    {
        for (int i = j; i < count - 1; i++)
        {
            NSString *a = [mArr objectAtIndex:j];
            NSString *b = [mArr objectAtIndex:i+1];
            if ([a isEqualToString:b])
            {
                NSLog(@"repeat = %@",[mArr objectAtIndex:i+1]);
                [mArr removeObjectAtIndex:i+1];
                count--;//数组长度发生变化
                i--;//没有这步.如果abcccd的情况就会跳过一个c
            }
        }
    }

    return mArr;
}

@end

2:

Student.h

#import <Foundation/Foundation.h>
@protocol OrderDelegate;

@interface Student : NSObject

@property(nonatomic,assign)id<OrderDelegate> delegate;

-(void)orderMeal;
@end




@protocol OrderDelegate <NSObject>
@required
-(void)order:(NSString *)aName
   withMoney:(int)aMoney;
@end

Student.m

#import "Student.h"

@implementation Student
@synthesize delegate = _delegate;

-(void)orderMeal
{
    if ([self.delegate conformsToProtocol:@protocol(OrderDelegate)])
    {
        [self.delegate order:@"腊味" withMoney:10];
    }
}


@end

 Waiter.h

#import <Foundation/Foundation.h>

#import "Student.h"
@interface Waiter : NSObject <OrderDelegate>

@end

Waiter.m

#import "Waiter.h"


@implementation Waiter

-(void)order:(NSString *)aName withMoney:(int)aMoney
{
    NSLog(@"买到了%d元的%@",aMoney,aName);
}

@end

AppDelegate.m

Waiter *w = [[Waiter alloc]init];
    
    Student *s = [[Student alloc]init];
    
    s.delegate = w;
    [s orderMeal];