OC-获取城市首字母

题目：解析根据文件里面的内容，读入一个城市，输出所在首字母
比如读入 长春 输出 c
读入 北京 输出 b

从如下文件解析

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>a</key>
    <array>
        <string>安吉</string>
        <string>安庆</string>
        <string>鞍山</string>
        <string>澳门</string>
    </array>
    <key>b</key>
    <array>
        <string>保定</string>
        <string>宝鸡</string>
        <string>包头</string>
        <string>北海</string>
        <string>北京</string>
        <string>蚌埠</string>
        <string>滨州</string>
    </array>
    <key>c</key>
    <array>
        <string>沧州</string>
        <string>长春</string>
        <string>常德</string>
        <string>长乐</string>
        <string>长沙</string>
        <string>常熟</string>
        <string>常州</string>
        <string>潮阳</string>
        <string>潮州</string>
        <string>承德</string>
        <string>成都</string>
        <string>郴州</string>
        <string>重庆</string>
        <string>滁州</string>
        <string>慈禧</string>
        <string>从化</string>
    </array>
</dict>
</plist>

本次思路

1.创建一个首字母和城市名称的一个类FirstLetterAndCity，其中有两个成员变量，一个位字符串类型，存储首字母，一个动态数组，存储该字母对应的所有城市。

//
//  FirstLetterAndCity.h
//  day16_OC5_城市首字母
//
//  Created by qianfeng on 15/6/15.
//  Copyright (c) 2015年 QF_Lpj. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface FirstLetterAndCity : NSObject
{
    NSString *_firstLetter;  //城市首字母
    NSMutableArray *_cityList; //城市集合
}
- (id)init;

//设置城市首字母
- (void)setFirstLetter:(NSString *)firstLetter;
- (NSString *)firstLetter;

//首字母和城市类的城市列表中添加城市
- (void)addCityList:(NSString *)cityName;
- (NSMutableArray *)cityList;


@end
------------------------------
//
//  FirstLetterAndCity.m
//  day16_OC5_城市首字母
//
//  Created by qianfeng on 15/6/15.
//  Copyright (c) 2015年 QF_Lpj. All rights reserved.
//

#import "FirstLetterAndCity.h"

@implementation FirstLetterAndCity

- (id)init
{
    if (self = [super init]) {
        _firstLetter = @"";
        _cityList = [[NSMutableArray alloc] init];
    }
    return self;
}

//设置城市首字母
- (void)setFirstLetter:(NSString *)firstLetter
{
    _firstLetter = firstLetter;
}
- (NSString *)firstLetter
{
    return _firstLetter;
}

//首字母和城市类的城市列表中添加城市
- (void)addCityList:(NSString *)cityName
{
    if (![cityName isEqualToString:@""]) {
        [self ->_cityList addObject:cityName];
    }
}
- (NSMutableArray *)cityList
{
    return _cityList;
}


@end

2.创建一个城市管理类，其中有一个动态数组的成员变量，用于存储所有FirstLetterAndCity类对象。

之后通过遍历管理类中的数组，对每一个FirstLetterAndCity对象中的数组再意义遍历，当对应的城市名称在其中有时，就返回该对象对应的城市首字母

//
//  ManagerCity.h
//  day16_OC5_城市首字母
//
//  Created by qianfeng on 15/6/15.
//  Copyright (c) 2015年 QF_Lpj. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "FirstLetterAndCity.h"

#define FilePath @"/Users/qianfeng/Desktop/day16_OC5_复合类设计/day16_OC5_城市首字母/城市首字母.txt"

@interface ManagerCity : NSObject
{
    NSMutableArray *_firstLetterAndCityList;  //用于存储城市集合和首字母  FirstLetterAndCity 对象
}

- (id)init;

- (NSString *)getFileAllString:(NSString *)filePath;

//输入一个城市名称，返回对应的首字母
- (NSString *)getFirstLetterByCityName:(NSString *)cityName;


+ (void)testManagerCity:(NSString *)cityName;



@end

---------------------------------------------------
//
//  ManagerCity.m
//  day16_OC5_城市首字母
//
//  Created by qianfeng on 15/6/15.
//  Copyright (c) 2015年 QF_Lpj. All rights reserved.
//

#import "ManagerCity.h"
#import "FirstLetterAndCity.h"

//声明一个匿名类别 实现私有化    
@interface ManagerCity ()

- (NSString *)getFLetterByCityName:(NSString *)cityName;

@end

@implementation ManagerCity

- (id)init
{
    if (self = [super init]) {
        _firstLetterAndCityList = [[NSMutableArray alloc] init];
    }
    return self;
}

//由路径生成一个字符串对象
- (NSString *)getFileAllString:(NSString *)filePath
{
    NSString *fileContent = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
    return fileContent;
}

//通过城市名称获取城市首字母
- (NSString *)getFirstLetterByCityName:(NSString *)cityName
{
    NSString *fileContent = [self getFileAllString:FilePath];
    NSArray *fileContentArray = [fileContent componentsSeparatedByString:@"
"];
    //首字母 城市名类
    FirstLetterAndCity *letterCity;
    if (fileContentArray) {
        for (NSString *item in fileContentArray) {
            if ([item isEqualToString:@""]) {
                continue;
            }
            else if([item containsString:@"<key>"])
            {
                letterCity = [[FirstLetterAndCity alloc] init];
                //<key>x</key> 获取'x'前后的位置坐标，由此获取到x
                NSRange rangeRight = [item rangeOfString:@">"];
                NSRange rangeLeft = [item rangeOfString:@"</"];
                [letterCity setFirstLetter:[item substringWithRange:NSMakeRange(rangeRight.location+1, rangeLeft.location-rangeRight.location-1)]];
                
            }else if([item containsString:@"<string>"])
            {
                //获取"<string>XX</string>"  XX之间的位置，并且由此获得对应的城市
                NSRange rangeRight = [item rangeOfString:@">"];
                NSRange rangeLeft = [item rangeOfString:@"</"];
                [letterCity addCityList:[item substringWithRange:NSMakeRange(rangeRight.location+1, rangeLeft.location-rangeRight.location-1)]];
            }
            //只有当碰到"</array>"时才说明走完了一个key 和 一列 string
            if (letterCity && [item containsString:@"</array>"]) {
                [self->_firstLetterAndCityList addObject:letterCity];
            }
        }
    }
    
    NSString *firstLetter = [self getFLetterByCityName:cityName];
    
    
    return firstLetter;
}

//当获取 _firstLetterAndCityList 列表时候，通过传入的城市名字获取到对应的城市首字母
- (NSString *)getFLetterByCityName:(NSString *)cityName
{
    //FirstLetterAndCity *flCity = [[FirstLetterAndCity alloc] init];
    for (FirstLetterAndCity *flCity in self->_firstLetterAndCityList) {
        for (NSString *item in [flCity cityList]) {
            if ([item isEqualToString:cityName]) {
                return [flCity firstLetter];
            }
        }
    }
    return @"NotFound";
}


+ (void)testManagerCity:(NSString *)cityName
{
    ManagerCity *mCity = [[ManagerCity alloc] init];
    NSString *firstLetter = [mCity getFirstLetterByCityName:cityName];
    if (![firstLetter isEqualToString:@"NotFound"]) {
        NSLog(@"%@",firstLetter);
    }else{
        NSLog(@"没有%@城市的首字母",cityName);
    }
}
134 @end