[学习笔记—Objective-C]《Objective-C 程序设计 第6版》第十五章 数字 字符串和集合

第十三章主要讲解C语言的语法，书中作者不提倡第一次阅读本书时阅读，故略过。
第十四章介绍Foundation框架，内容比较少，也就此略过。

Part 1. 数字对象

• 基本的数据类型不是对象，因此不能给他们发信息。但是有的时候需要将这些值作为对象使用：NSArry创建的数组存储的值必须是对象，因此数据类型无法直接存储到数组中，需要NSNumber类，依据数据的类型创建对象。

• NSNumber类：每种基本数据类型，NSNumber的类方法都能为它创建一个NSNumber对象。

        NSNumber *myNumber, *floatNumber, *intNumber; //NSNumber对象        NSInteger myInt; //NSInteger:基本数据类型的typedef(64位long或者32为int)        //创建integer 整型                intNumber = [NSNumber numberWithInteger:100];        myInt = [intNumber integerValue];//获取存储在intNumber中的整型值        NSLog(@"%li", (long)myInt);      //将myInt转换为long型        //创建long 型值                myNumber = [NSNumber numberWithLong:0xabcdf];        NSLog(@"%lx", [myNumber longValue]);        //创建char 型值        myNumber = [NSNumber numberWithChar:'X'];        NSLog(@"%c", [myNumber charValue]);        //创建float 型值                floatNumber = [NSNumber numberWithFloat:100.00];        NSLog(@"%g", [floatNumber floatValue]);        //创建double 型值                myNumber = [NSNumber numberWithDouble:12345e+15];        NSLog(@"%lg", [myNumber doubleValue]);        //发生错误：存储的类型和提取的类型应该一致        NSLog(@"%li", (long) [myNumber integerValue]);        //验证两个number是否相等                if ([intNumber isEqualToNumber:floatNumber] == YES)            NSLog(@"Numbers are equal");        else            NSLog(@"Numbers are not equal");        //验证一个Number是否小于，等于，或大于另一个Number        if ([intNumber compare:myNumber] == NSOrderedAscending)            NSLog(@"First number is less than second");        //相等：NSOrderdSame        //大于：NSOrderdDescending

• 注意：不能修改前面创建的NSNumber的值：所有数字对象都必须是新创建的。

  • 对NSNumber类调用numberWith方法
  • 对alloc方法的结果调用initWith方法

• 通过@表达式创建数字对象

        NSNumber *myNumber, *floatNumber, *intNumber;        NSInteger myInt;        //整型 integer        intNumber = @100;        myInt = [intNumber integerValue];        NSLog(@"%li", (long) myInt);        //长整型long value        myNumber = @0xabcdefL;        NSLog(@"%lx", [myNumber longValue]);        myNumber = @'X';        NSLog(@"%c", [myNumber charValue]);        //浮点型        floatNumber = @100.0f;        NSLog(@"%g", [floatNumber floatValue]);

Part 2. 字符串对象

Part 2.1 NSLog函数

        //常量字符串对象 Programming is fun 被赋值给NSString变量str        NSString *str = @"Programming is fun";         NSLog(@"%@",str);

Part 2.2 可变对象与不可变对象

• 处理不可变对象

        NSString *str1 = @"This is string A"; //常量字符串对象 指向了内存中的某处字符串对象        NSString *str2 = @"This is string B"; //常量字符串        NSString *res;        NSComparisonResult compareResult;     //保存结果                //将一个字符串赋复制到另一个字符串                res = [NSString stringWithString:str1]; //str1 赋值给res，字符串内容的复制，产生新的字符串，str1和res指向两个不同的字符串对象;而res=str1:同一对象的另一个引用        //将一个字符串复制到另一个字符串的末尾                str2 = [str1 stringByAppendingString:str2]; //产生新的字符串对象，原字符串对象str1和str2没有被更改：因为是不可变字符串对象               //将字符串转换为大写               res = [str1 uppercaseString]; //res指向新字符串对象（大写），str1仍然指向原来的字符串对象               //字符串转换为小写                res = [str1 lowercaseString]; //原来的大写字符不再被引用。小写字符串的引用存在res中

        NSString *str1 = @"This is string A";        NSString *str2 = @"This is string B";        NSString *res;         NSRange subRange;//subRange是结构变量        //从字符串中提取前三个字符                res = [str1 substringToIndex:3];//创建一个子字符串，首字符到指定的索引数。0，1，2        NSLog(@"First 3 chars of str1: %@", res);        //提取从索引5开始直到结尾的子字符串                res = [str1 substringFromIndex:5];//返回一个子字符串，指定索引字符到字符串结尾        //提取从索引8开始到索引13的字符串（6个字符：13-8+1 = 6）                res = [ [str1 substringFromIndex:8] substringToIndex:6];        NSLog(@"Chars from index 8 through 13: %@", res);        //更简单的方法                res = [str1 substringWithRange: NSMakeRange(8, 6)];        NSLog(@"Chars from index 8 through 13: %@",res);        //从另一个字符串中查找一个字符串        subRange = [str1 rangeOfString: @"string A"];        NSLog(@"String is at index %lu, lenth is %lu", subRange.location, subRange.length);//结构成员操作符:(.)

• 可变字符串

        NSString *str1 = @"This is string A";        NSString *search, *replace;        NSMutableString *mstr; //用来存储在程序执行过程中值可能更改的字符串对象        NSRange substr;        //从不可变字符串创建可变字符串        mstr = [NSMutableString stringWithString: str1]; //返回可变的字符串对象        //插入字符        [mstr insertString:@" mutable" atIndex:7];        //插入末尾进行有效拼接        [mstr insertString:@" and string B" atIndex:[mstr length]];        //直接在末尾添加        [mstr appendString:@" and string C"];        //根据范围范围删除子字符串 从索引数16开始删除13个字符。        [mstr deleteCharactersInRange: NSMakeRange(16, 13)];        //查找然后将其删除                substr = [mstr rangeOfString:@"string B and "];        if (substr.location != NSNotFound){            [mstr deleteCharactersInRange:substr];            NSLog(@"%@", mstr);        }        //直接设置为可变的字符串                [mstr setString:@"This is string A"];        NSLog(@"%@", mstr);        //替换一些字符        [mstr replaceCharactersInRange:NSMakeRange(8, 8) withString:@"a mutable string"];        //查找和替换        search = @"This is";        replace = @"An example of";        substr = [mstr rangeOfString:search];        if (substr.location != NSNotFound){            [mstr replaceCharactersInRange:substr withString:replace];            NSLog(@"%@",mstr);        }        //查找和替换所有的匹配项        search = @"a";        replace = @"X";        substr = [mstr rangeOfString:search];        while (substr.location != NSNotFound) {            [mstr replaceCharactersInRange:substr withString:replace];            substr = [mstr rangeOfString:search];        }        NSLog(@"%@", mstr);

Part 3. 数组对象

不可变数组：NSArray
可变数组：NSMutableArray

int main(int argc, const char * argv[]) {    int i;    @autoreleasepool {    //创造和返回一个数组 : arrayWithObjects    NSArray *monthNames = [ NSArray arrayWithObjects:                   @"January", @"February", @"March", @"April", @"May",@"June",@"July",@"August",@"September",@"October", @"November", @"December", nil]; //12个字符串，索引从0开始 0~11        //列出数组中所有的元素                NSLog(@"Month  Name");        NSLog(@"=====  ====");                for (i = 0; i < 12; ++i)                   NSLog(@"%2i     %@", i+1, [monthNames objectAtIndex:i]);         // objectAtIndex:索引元素    }    return 0;}

• 简单创建NSArray对象：

//创建NSArray对象@[elem1, elem2, ... elemn];//引用数组元素array [index]; //等价于：[array objectAtIndex: index]//将对象的引用存储到数组中array [index] = object; //等价于：[array setObject: object forIndex: index]

• 创建一个包含各月份的数组

int main(int argc, const char * argv[]) {    int i;    @autoreleasepool {        //创建一个包含各月份名称的数组        NSArray *monthNames = @[ @"January", @"February", @"March", @"April", @"May", @"June", @"July",@"August",@"September",@"October", @"November", @"December"];        //列出数组中的所有元素                NSLog(@"Month Name");        NSLog(@"===== ====");        for (i = 0; i<12; ++i)        {            NSLog(@" %2i  %@", i+1, monthNames[i]);        }           }    return 0;}

• 数字对象的数组

        NSMutableArray *numbers = [NSMutableArray array]; //创建空的可变数组对象，数组元素的个数并未指定        int i;        //创建0~9数字的数组                for (i = 0; i < 10; ++i)        {            numbers[i] = @(i); //在数组末尾添加一个对象：[numbers addObject: @(i)];        }        //显示数组每个元素的值                for (i = 0; i < 10; ++i)        {            NSLog(@"%@", numbers[i]);        }        //使带有%@格式的NSLog显示               NSLog(@"====== Using a single NSLog");        NSLog(@"%@", numbers);

• 地址簿实例:
  一个可以进行添加，删除，搜索，排序地址卡片(姓名+邮件)的地址簿

AddressCard.h

#import <Foundation/Foundation.h>@interface AddressCard : NSObject@property (copy, nonatomic) NSString *name, *email;-(void) setName:(NSString *) theName andEmail: (NSString *) theEmail; //设置名字，邮件(字符串)-(void) print; //打印名片-(NSComparisonResult) compareNames: (id) element;//比较两个字符串@end

AddressCard.m

#import "AddressCard.h"@implementation AddressCard@synthesize name, email;-(void) setName:(NSString *) theName andEmail: (NSString *) theEmail{    self.name = theName;    self.email = theEmail;}-(NSComparisonResult) compareNames: (id) element{    return [name compare: [element name]];//两个字符串的比较，返回比较结果}-(void) print {    NSLog(@"==============================");    NSLog(@"|                            |");    NSLog(@"|  %-31s  |",  [name UTF8String]);    NSLog(@"|  %-31s  |",  [email UTF8String]);    NSLog(@"|                            |");    NSLog(@"==============================");}@end

AddressBook.h

#import <Foundation/Foundation.h>#import "AddressCard.h"@interface AddressBook : NSObject@property (nonatomic, copy) NSString *bookName;@property (nonatomic, strong) NSMutableArray *book;-(instancetype) initWithName: (NSString *) name; //设置初始数组-(void) addCard: (AddressCard *) theCard; //向地址簿添加名片-(void) removeCard: (AddressCard *) theCard;//向地址簿移除名片-(AddressCard *) lookup: (NSString *) theName; //查找名片-(int) entries; //获取名片的数量-(void) list;   //显示地址簿的全部内容-(void) sort;   //排序地址簿中的名片@end

AddressBook.m

#import "AddressBook.h"@implementation AddressBook@synthesize bookName, book;//设置addressbook的名称和一个空的addressbook-(instancetype) initWithName:(NSString *)name //返回值类型定义为:一般的对象类型{    if (self) {        bookName = [ NSString stringWithString:name ];//将方法参数传递过来的字符串复制一份存储在实例变量bookName中        book = [ NSMutableArray array ];//再创建一个空的NSMutableArray对象赋值给book    }    return self;}-(instancetype) init{    return [self initWithName:@"NoName"];}-(void) addCard:(AddressCard *)theCard //将AdrressCard作为参数，添加到地址簿中{    [book addObject: theCard];}-(void) removeCard: (AddressCard *) theCard{    [book removeObjectIdenticalTo: theCard];}-(int) entries //返回地址簿中存储的地址卡片数目{    return [book count]; //count方法返回数组元素的个数;}-(void) list{    NSLog(@"========== Contents of: %@ =========", bookName);    for ( AddressCard *theCard in book) //book数组的每个元素序列使用快速枚举技术        NSLog(@"%-20s   %-32s", [theCard.name UTF8String],[theCard.email UTF8String]);    NSLog(@"=======================================================");}-(void) sort{    [book sortUsingSelector:@selector(compareNames:)]; //sortUsingSelector:比较数组中的两个元素}-(AddressCard *) lookup: (NSString *) theName{    for (AddressCard *nextCard in book) //快速枚举        if ( [nextCard.name caseInsensitiveCompare: theName] == NSOrderedSame)            return nextCard;    return nil;}@end

main:

#import <Foundation/Foundation.h>#import "AddressBook.h"#import "AddressCard.h"int main(int argc, const char * argv[]) {    @autoreleasepool {        NSString *aName = @"Julia";        NSString *aEmail = @"[e-mail]";        NSString *bName = @"Tony";        NSString *bEmail = @"[e-mail]";        NSString *cName = @"Stephen";        NSString *cEmail = @"[e-mail]";        NSString *dName = @"Jamie";        NSString *dEmail = @"[e-mail]";        AddressCard *card1 = [[AddressCard alloc] init];        AddressCard *card2 = [[AddressCard alloc] init];        AddressCard *card3 = [[AddressCard alloc] init];        AddressCard *card4 = [[AddressCard alloc] init];        //创建一个新的地址簿        AddressBook *myBook = [[AddressBook alloc] initWithName:@"Linda's Address Book " ];        AddressCard *myCard;        //创建四个卡片        [card1 setName:aName andEmail:aEmail];        [card2 setName:bName andEmail:bEmail];        [card3 setName:cName andEmail:cEmail];        [card4 setName:dName andEmail:dEmail];        //将地址卡片添加到地址簿        [myBook addCard:card1];        [myBook addCard:card2];        [myBook addCard:card3];        [myBook addCard:card4];        //列出未排序的地址簿        [myBook list];        //进行排序并在此列出        [myBook sort];        [myBook list];        //通过名字查找一个        NSLog(@"Lookup : Stephen:");        myCard = [myBook lookup: @"Stephen"];        if (myCard != nil) {            [myCard print];        }        else            NSLog(@"Not Found!");        //从电话簿中删除条目        [myBook removeCard:myCard];        [myBook list];    }    return 0;}

Part 4. 词典对象

• 词典：键—对象对组成的数据集合，通过对象的键从词典中获取对象。和键关联的值可以是任何类型，但不能使nil。
• 词典可以固定,可以可变:动态添加和删除，使用键检索词典，可以枚举内容。

        NSMutableDictionary *glossary = [ NSMutableDictionary dictionary];//创建空的可变词典        //存储一个条目在类别中           [glossary setObject:@"A class defined so other classes can inherit from it" forKey:@"abstract class"];               //检索并显示                NSLog(@"abstract class: %@", [glossary objectForKey:@"abstract class"])        //[dict objectForKey: key] 等同于 dict[ key ]        //[dict setObject: object forKey: key] 等同于： dict[key] = object

• 枚举词典

//创建对象-键对的数组       NSDictionary *glossary = [NSDictionary dictionaryWithObjectsAndKeys:                     @"A class defined so other classes can inherit from it",                     @"abstract class",                     @"To implement all the methods defined in a protocol",                     @"adopt",                     @"Storing an object for later use",                     @"achiving",                     nil];        for (NSString *key in glossary) //枚举            NSLog(@"%@:%@", key, [glossary objectForKey:key]);

Part 5. 集合对象

• set：单值对象集合
  
  • 可变，不可变
  • 搜索，添加，删除集合中的成员，比较两个集合，计算两个集合的交集和并集

        NSMutableSet *set1 = [NSMutableSet setWithObjects:                              @1, @3, @5, @10, nil];        NSSet *set2 = [NSSet setWithObjects:                       @-5, @100, @3, @5, nil];        NSSet *set3 = [NSSet setWithObjects:                       @12, @200, @3, nil];        NSLog(@"set1:");        [set1 print];        NSLog(@"set2:");        [set2 print];        //相等性测试        if ([set1 isEqualTo:set2] == YES) {            NSLog(@"set1 equals set2");        } else {            NSLog(@"set1 is not equat to set2");        }        //成员测试        if ([set1 containsObject:@10]) {            NSLog(@"set1 contains 10");        } else {            NSLog(@"set1 does to contain set2");        }        if ([set2 containsObject:@10]) {            NSLog(@"set2 contains 10");        } else {            NSLog(@"set2 does to contain set2");        }        //在可变集合set1中添加和移除对象        [set1 addObject:@4];        [set1 removeObject:@10];        NSLog(@"set1 after adding 4 and removing 10:");        [set1 print];        //获得两个集合的交集        [set1 intersectSet:set2];        NSLog(@"set1 inserct set2: ");        [set1 print];        //获得两个集合的并集        [set1 unionSet:set3];        NSLog(@"set1 union set3: ");        [set1 print];