[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 = @"julia@gmail.com";

NSString *bName = @"Tony";
NSString *bEmail = @"tony@gmail.com";

NSString *cName = @"Stephen";
NSString *cEmail = @"steve@gmail.com";

NSString *dName = @"Jamie";
NSString *dEmail = @"jamie@gmail.com";

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];