http://www.translate.com"];
1.以某些字符开头 hasPrefix:)#> 后面填写的是字符串对象 @“”;返回值是一个bool类型 0或者1
BOOL isPrefix = [str4 hasPrefix:@"http"];
2,.以某些字符结束 hasSuffix:)#> 后面填写的是字符串对象 @“”;返回值是一个bool类型 0或者1
BOOL isSuffix = [str4 hasSuffix:@"com”];
3.查找指定字符串的范围 rangeOfString:)#> - (NSRange)rangeOfString:(NSString )aString NSRange结构体重新命名得到的 返回值为:range.location 和range.length 只查找有没有 而不管有几个 如果有返回开始下表和长度
NSRange range/(NSString NSStringFromRange)和前面的等价/ = [str4 rangeOfString:@"http"];
if (range.length == 0) {
NSLog(@"没有相关的字符串");
}else{
//将NSRange 结构体类型变量直接转换成字符串对象输出
A structure used to describe a portion of a series—such as characters in a string or objects in an NSArray object.
/ typedef struct _NSRange {
NSUInteger location;
NSUInteger length;
} NSRange;
/
NSLog(@"%@",NSStringFromRange(range)); {0,4}返回值
//NSLog(@"locatio = %lu,length = %lu",range.location,range.length);等价于上面的方法

NSString * NSStringFromRange (
NSRange range);
}

1. 字符串截取 从给定下表到结束 substringFromIndex substringToIndex substringWithRange 由于操作的是不可变的字符串 这里操作的是副本
   NSString str5 = [NSString stringWithFormat:@"lanou is a big company"]; //便利构造器的方法 快速产生字符串对象
   1.获取给定下标之后的字符串,包含指定下标对应的字符 空格也要算在内 from包含
   //例如要获取company
   NSString subString1 = [str5 substringFromIndex:15];
   NSLog(@"subString = %@",subString1);
   2.获取给定下标之前的字符串,不包含指定下标对应的字符 空格也要算在内 to不包含
   // 如:lanou
   NSString *subString2 = [str5 substringToIndex:5];
   NSLog(@"subString = %@",subString2);

3.获取制定一个范围的字符串 substringWithRange Returns a string object containing the characters of the receiver that lie within a given range.

• (NSString )substringWithRange:(NSRange)aRange
  //例如获取:lanou 利用NSMakeRange(0, 5)
  NSString subString3 = [str5 substringWithRange:NSMakeRange(0, 5)];
  NSLog(@"subString3 = %@",subString3);
  4.字符串拼接 stringByAppendingFormat Returns a string made by appending to the receiver a string constructed from a given format string and the following arguments.
• (NSString )stringByAppendingFormat:(NSString )format, ...
  stringByAppendingString Returns a new string made by appending a given string to the receiver.
• (NSString )stringByAppendingString:(NSString )aString
  NSString str6 = [NSString stringWithFormat:@"lanou"];
  //lanou 后拼接 henan
  NSString newStr6 = [str6 stringByAppendingString:@"henan"];//不可以出现格式串
  NSLog(@"newStr6 = %@",newStr6);
  //lanou 后拼接 henan9ban
  NSString newStr7 = [str6 stringByAppendingFormat:@"henan%dban",9];//可以出现格式串
  NSLog(@"newStr7 = %@",newStr7);
  NSString newStr8 = [str6 stringByAppendingFormat:@"%@",newStr7];//特别注意可以拼接对象
  NSLog(@"newStr8 = %@",newStr8);

5.替换字符串 stringByReplacingOccurrencesOfString: withString: Returns a new string in which all occurrences of a target string in the receiver are replaced by another given string.

• (NSString )stringByReplacingOccurrencesOfString:(NSString )target withString:(NSString )replacement
  NSString str8 = [NSString stringWithFormat:@"lan ouououououououou isabigcompany"];
  //(1)将ou替换成nb
  NSString newStr9 = [str8 stringByReplacingOccurrencesOfString:@"ou"withString:@"牛逼"]; //换掉谁谁在前 换上谁 谁在前
  NSLog(@"newStr8 = %@",newStr9);
  //2.只将第一个ou换成牛逼 如果替换两个 就写两次 牛逼
  NSString newStr10 = [str8 stringByReplacingCharactersInRange:NSMakeRange(4, 2) withString:@"牛逼"];
  NSLog(@"%@",newStr10);

6.字符串比较 返回值为 枚举类型
Returns the result of invoking compare:options:range: with no options and the receiver’s full extent as the range.

• (NSComparisonResult)compare:(NSString *)aString
  NSComparisonResult 返回值类型 枚举类型
  
  NSComparisonResult result = [@"111" compare:@"222"];//前一个比后一个小 升序返回 -1
  NSLog(@"%ld",result);

7.将数字转为字符串对象
NSString *str12 = [NSString stringWithFormat:@"%f",5.2];//将5.2转换为字符串对象
1.字符串大小写转换

8.字符串的大小写转换函数

1.将@"lan ghasgda HGASIDHH JHFWIEFH J OU"全部转换成大写 uppercaseString Returns a uppercased(大写字母印刷 ) representation of the receiver.

• (NSString *)uppercaseString 无参数 有返回值 消息传送机制

  NSString *upperString = [@"lan ghasgda HGASIDHH JHFWIEFH J  OU" uppercaseString];
  NSLog(@"upperString = %@",upperString);

2.将@"lan SJA Hjknjkjnkdj sdjkjsd OU"全部转换成小写 lowercaseString Returns lowercased representation of the receiver.

• (NSString )lowercaseString 无参数 有返回值 消息传送机制
  NSString lowerString = [@"lan SJA Hjknjkjnkdj sdjkjsd OU" lowercaseString];
  NSLog(@"lowerString = %@",lowerString);
  3.将@"lan bdfh bsdjksbajf jksdbfjkwdbfjk OU"首转换成大写 capitalizedString Returns a capitalized(首字母大写的) representation of the receiver.
• (NSString )capitalizedString 无参数 有返回值 消息传送机制
  NSString capitilizedString = [@"lan bdfh bsdjksbajf jksdbfjkwdbfjk OU" capitalizedString];
  NSLog(@"capitilizedString = %@",capitilizedString);
  常用的可变字符串处理实例方法

NSMutableString 这里需要注意的是该方法的处理方式是在原字符串上直接进行修改
1.– appendFormat:
Adds a constructed string to the receiver.
添加一个字符串构造的接收器

• (void)appendFormat:(NSString )format …
  NSMutableString str = [NSMutableString stringWithFormat:@"lanouhenan"];
  //1.在原字符串的基础上拼接Frank appendFormat 对于字符串的修改都是在字符串基础上修改,所以修改完的字符串内容发生变化 所以不需要返回值
  [str appendFormat:@"Frank"];
  NSLog(@"%@",str);// lanouhenanFrank

2.– appendString:
Adds to the end of the receiver the characters of a given string.
增加了接收器的端部在给定的字符串的字符

• (void)appendString:(NSString *)aString

  NSMutableString *str = [NSMutableString stringWithFormat:@"lanouhenan”];
  //2.在原字符串的基础上拼接Frank
  [str appendString:@"Frank”];
  NSLog(@"%@",str);// lanouhenanFrankFrank
  •

•
• 3.– deleteCharactersInRange:
•
Removes from the receiver the characters in a given range.
从接收机中删除给定范围内的字符

• (void)deleteCharactersInRange:(NSRange)aRange

NSMutableString *str = [NSMutableString stringWithFormat:@"lanouhenan”];
//3.删除字符串 在原字符串基础上删除
//如 删除 henan
[str deleteCharactersInRange:NSMakeRange(5, 5)];
NSLog(@"%@",str);//lanouhenanFrankFrank
•
•
• 4.– insertString:atIndex:
•
Inserts into the receiver the characters of a given string at a given location.
插入到接收器给定的字符串中的字符在给定的位置。

• (void)insertString:(NSString )aString atIndex:(NSUInteger)anIndex
  NSMutableString str = [NSMutableString stringWithFormat:@"lanouhenan”];
  //4.插入字符串 在原字符串基础上插入
  [str insertString:@"henan" atIndex:5];
  NSLog(@"%@",str);//lanouhenanFrankFrank

• 5.– replaceCharactersInRange:withString:
•
Replaces the characters from aRange with those in aString.
取代了aRange人物与那些在ASTRING。

• (void)replaceCharactersInRange:(NSRange)aRange withString:(NSString )aString
  NSMutableString str = [NSMutableString stringWithFormat:@"lanouhenan”];
  //5.替换字符串 在元字符串基础上将Frank替换成Duck
  [str replaceCharactersInRange:NSMakeRange(10, 5) withString:@"Duck"];
  NSLog(@"%@",str);//lanouhenanDuckFrank

• 6.– replaceOccurrencesOfString:withString:options:range:
•
Replaces all occurrences of a given string in a given range with another given string, returning the number of replacements.
替换在给定的范围内与其他给定的字符串给定的字符串的所有匹配，返回替换的数量。

• (NSUInteger)replaceOccurrencesOfString:(NSString )target withString:(NSString )replacement options:(NSStringCompareOptions)opts range:(NSRange)searchRange
  NSMutableString str1 = [NSMutableString stringWithFormat:@"lanouhenanjdsfhdfhjdfsdjfj”]; //可变的字符串处理函数
  NSString str13 = [str1 stringByReplacingCharactersInRange:NSMakeRange(10, 5) withString:@"Duck”];//不可变的字符串处理函数
  NSLog(@"%@",str1);//lanouhenanjdsfhdfhjdfsdjfj
  NSLog(@"%@",str13);//lanouhenanDuckdfhjdfsdjfj
  //这里可以结合函数的传值调用和传址调用,需要明白的NSString在处理字符串对象时是将字符串拷贝副本,针对副本进行操作 所以上面的返回值里有两中不同的结果.

• 7.– setString:
•

Replaces the characters of the receiver with those in a given string.
替换与一个给定的字符串中的接收器的特征。

• (void)setString:(NSString )aString
  NSMutableString str = [NSMutableString stringWithFormat:@"lanouhenan”];
  注:本文中的所有代码需要前后结合来看.
  数组的价值:(1)存数多个元素(2)存储元素只能是对象,对象可以是不同类型(3)数组是一个有序的集合(4)数组中的元素可以重复,而且重复的元素可以成为数组元素
  NSArray 不可变数组对象
  Creating an Array 利用便利构造器方法

  1. arrayWithObjects:
     Creates and returns an array containing the objects in the argument list.
     创建并返回包含在参数列表中的对象的数组。
• (instancetype)arrayWithObjects:(id)firstObj,,…

1. initWithObjects:
   Initializes a newly allocated set with members taken from the specified list of objects.
   初始化一个新分配的一套从对象的指定名单中的成员。

• (instancetype)initWithObjects:(id)firstObj, …
  创建数组对象
  //1.使用便利构造器
  //1.arrayWithObjects 元素与元素之间用逗号间隔 输出格式 (aa,bb,cc)
  //2.以nil结束 nil后面的元素都不会放入数组中
  NSArray arr1 = [NSArray arrayWithObjects:@"aa",@"bb",@"5",nil,@"cc", nil];
  NSLog(@"arr1 = %@",arr1);//arr1 = (aa,bb,5)
  //2.使用初始化方法
  NSArray arr2 = [[NSArray alloc] initWithObjects:@"aa",@"bb",@"5",nil,@"cc",nil];
  NSLog(@"arr2 = %@",arr2);//arr2 = (aa,bb,5)

1. count:
   Returns the number of objects currently in the array.
   返回当前阵列的对象的数量。

• (NSUInteger)count
  获取元素个数
  NSUInteger count = [arr2 count];
  NSLog(@"count = %lu",count); //count = 3;

1. objectAtIndex:通过下标取元素
   Returns the object at the specified index of the set.
   返回集合的指定索引处的对象。

• (id)objectAtIndex:(NSUInteger)index

1. firstObject:
   Returns the first object in the array.
   返回的数组中的第一个对象。

• (id)firstObject

1. lastObject:
   Returns the last object in the ordered set.

返回的有序集合的最后一个对象。

• (id)lastObject
  根据索引值获取对象
  //(1)获取制定下标的元素
  NSString str = [arr2 objectAtIndex:1];
  NSLog(@"str = %@",str);//str = bb;
  //(2)获取数组中第一个元素 //The first object in the array. If the array is empty, returns nil. first和last方法比objectAtIndex更加安全,当数组元素为空时会返回null,而objectAtIndex会造成程序的crash.即数组下标越界.
  NSString str1 = [arr2 firstObject];
  NSLog(@"str1 = %@",str1);//str1 = aa
  NSString str2 = [arr2 objectAtIndex:0];
  NSLog(@"str2 = %@",str2);//str2 = aa
  //(3)获取数组中最后个元素
  NSString str3 = [arr2 lastObject];
  NSLog(@"str3 = %@",str3);//str3 = 5

7.indexOfObject:通过对象返回下标
Returns the index of the specified object.
返回指定对象的索引。

• (NSUInteger)indexOfObject:(id)object
  获取数组对象在数组中的索引值; Returns the lowest index whose corresponding array value is equal to a given object.数组中的元素可以重复,返回的为第一个.
  NSUInteger index = [arr2 indexOfObject:@"5"];
  NSLog(@"index = %lu",index);//index = 2

1. containsObject:判断某一个对象是否存在于数组中
   Returns a Boolean value that indicates whether a given object is present in the set.
   返回一个布尔值，表示给定的对象是否存在于集合中。

• (BOOL)containsObject:(id)anObject
  判断是否包含某个对象. Returns a Boolean value that indicates whether a given object is present in the set.//返回值为bool类型.
  BOOL isExist = [arr2 containsObject:@"aa"];
  NSLog(@"isExist = %d",isExist);//isExist = 1

1. sortedArrayUsingSelector:
   Returns an array that lists the receiving array’s elements in ascending order, as determined by the comparison method specified by a given selector.
   • (NSArray )sortedArrayUsingSelector:(SEL)comparator
     数组排序
     NSArray sortArr = [arr2 sortedArrayUsingSelector:@selector(compare:)];//这里传入的是比较方法
     NSLog(@"sortArr = %@", sortArr);

10.forin

快速遍历(快速枚举)
for (int i = 0; i NSString str4 = [arr2 objectAtIndex:i];
NSLog(@"%@",str4);
}
/
for (type object(数组元素类型 对象名字) in collection(集合即:要取元素的数组)) {
statements 输出语句
} forin 快速遍历,用于将集合中的元素遍历出来.
/

    for (NSString *str4 in arr2) {
        NSLog(@"%@",str4);
    }

NSMutableArray 可变的数组对象处理函数
首先创建数组对象,然后针对数组对象进行操作
//创建数组对象
NSMutableArray *arr1 = [[NSMutableArray alloc] initWithObjects:@"aa",@"bb",@"cc",@"vbvh"@"jd",@"jhsfcu",@"dfdh", nil];

1.addObject:
Inserts a given object at the end of the array.

• (void)addObject:(id)anObject
  //1.添加元素
  [arr1 addObject:@"Frank"];
  NSLog(@"arr1 = %@",arr1);

2.insertObject:atIndex:
Inserts a given object into the array's contents at a given index.

• (void)insertObject:(id)anObject atIndex:(NSUInteger)index
  //2.插入元素 将Duck添加到aa的后面
  [arr1 insertObject:@"Duck" atIndex:1];
  NSLog(@"arr1 = %@",arr1);

1. removeAllObjects
   Empties the array of all its elements.
   • (void)removeAllObjects
     4.removeObjectAtIndex:
     Removes the object at index .
   • (void)removeObjectAtIndex:(NSUInteger)index
     //3.删除元素
     //1.将Duck删除
     [arr1 removeObjectAtIndex:3];
     NSLog(@"arr1 = %@",arr1);
     //2.删除所有元素
     // [arr1 removeAllObjects];
     // NSLog(@"arr1 = %@",arr1);

5.replaceObjectsInRange:withObjectsFromArray:range:
Replaces the objects in the receiving array specified by one given range with the objects in another array specified by another range.

• (void)replaceObjectsInRange:(NSRange)aRange withObjectsFromArray:(NSArray *)otherArray range:(NSRange)otherRange
  //4.替换元素
  //将Frank替换成"shuaige"
  [arr1 replaceObjectAtIndex:6 withObject:@"shuaige"];
  NSLog(@"arr1 = %@",arr1);

6.exchangeObjectAtIndex:withObjectAtIndex:
Exchanges the objects in the array at given indices.

• (void)exchangeObjectAtIndex:(NSUInteger)idx1(下标) withObjectAtIndex:(NSUInteger)idx2(下标)
  //5.交换指定的位置
  [arr1 exchangeObjectAtIndex:0 withObjectAtIndex:2];
  NSLog(@"arr1 = %@",arr1);

7.sortUsingSelector:
Sorts the array’s elements in ascending order, as determined by the comparison method specified by a given selector.

• (void)sortUsingSelector:(SEL)comparator
  //6.对原数组进行排序 按照ASCII码进行排序
  [arr1 sortUsingSelector:@selector(compare:)];
  NSLog(@"arr1 = %@",arr1);

//7.快速遍历
for (NSString *str5 in arr1) {
NSLog(@"%@",str5);
}
//如果数组中元素类型不同,输出时使用统一的泛型 id 可代表所有的对象类型.
for (id str5 in arr1) {
NSLog(@"%@",str5);
}
数值对象 NSNumber
1.numberWithChar:
Creates and returns an NSNumber object containing a given value, treating it as a signed char.

• (NSNumber *)numberWithChar:(char)value

2.charValue
Returns the receiver’s value as a char.

• (char)charValue
  //将基本数据类型转化成数值对象
  //1.定义接本数据类型变量
  char a = 'f';
  int b = 20;
  short c = 100;
  long d = 1000;
  float e = 12.345;
  double f = 10.2222;
  BOOL isTrue = YES;
  //2.将基本数据类型转换成数据对象 全部转换成对应的数值 存储在堆区
  //相当于中介
  NSNumber a1 = [NSNumber numberWithChar:a ];
  NSNumber a2 = [NSNumber numberWithInt:b ];
  NSNumber a3 = [NSNumber numberWithShort:c ];
  NSNumber a4 = [NSNumber numberWithLong:d ];
  NSNumber a5 = [NSNumber numberWithFloat:e ];
  NSNumber a6 = [NSNumber numberWithDouble:f ];
  NSNumber a7 = [NSNumber numberWithBool:isTrue];
  NSArray arr = [NSArray arrayWithObjects:a1,a2,a3,a4,a5,a6,a7 ,nil];
  NSLog(@"%@",arr);//打印数组
  //打印数值对象
  NSLog(@"%@",a1);
  NSLog(@"%@",a2);
  NSLog(@"%@",a3);
  NSLog(@"%@",a4);
  NSLog(@"%@",a5);
  NSLog(@"%@",a6);
  NSLog(@"%@",a7);
  //3.将NSNumber转换成基本数据
  char b1 = [a1 charValue];
  NSLog(@"%c",b1);
  int b2 = [a2 intValue];
  NSLog(@"%d",b2);
  //4.NSNumber类型数据的比较
  NSLog(@"%ld",[a1 compare:a2]);//注意对象比较对向

上述具体结果如下:
2014-08-07 18:59:26.555 LessonNnumber[8367:303] (
102,
20,
100,
1000,
"12.345",
"10.2222",
1
)
2014-08-07 18:59:26.556 LessonNnumber[8367:303] 102
2014-08-07 18:59:26.557 LessonNnumber[8367:303] 20
2014-08-07 18:59:26.557 LessonNnumber[8367:303] 100
2014-08-07 18:59:26.558 LessonNnumber[8367:303] 1000
2014-08-07 18:59:26.558 LessonNnumber[8367:303] 12.345
2014-08-07 18:59:26.558 LessonNnumber[8367:303] 10.2222
2014-08-07 18:59:26.559 LessonNnumber[8367:303] 1
2014-08-07 18:59:26.559 LessonNnumber[8367:303] f
2014-08-07 18:59:26.559 LessonNnumber[8367:303] 20
2014-08-07 18:59:26.560 LessonNnumber[8367:303] 1
http://developer.51cto.com/art/201407/444542_1.htm

24.字典
1.字典 作用:(1)存储多个数据 (2)用来存储的数据具有一一对应关系(使用key和value来标识) (3)对于字典中的一对键值对叫做字典中的元素,也就一个条目,只要是对象就可以,不做具体的数据类类型的限制4.字典是无序的(字典中关键字key是唯一标示的 一个key只能对应一个value,一个value可以对应多个key)
2.创建不可变字典对象 {元素 ;号间隔}不可变的字典一旦创建就不能修改为只读模式.
1.便利构造器的方法 这里要注意:键值对是成对出现的 到nil结束
dictionaryWithObjectsAndKeys +号方法 用于创建一个对象 快速创建 Creates and returns a dictionary containing entries constructed from the specified set of values and keys.

• (instancetype)dictionaryWithObjectsAndKeys:(id)firstObject, , ...
  NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:@"zhgds",@"name",@20,@"hight",@12,@"age",nil];

  NSLog(@"%@",dic);

2.初始化对象的方法 -号方法 开辟空间 初始化对象 initWithObjectsAndKeys Initializes a newly allocated dictionary with entries constructed from the specified set of values and keys.

• (instancetype)initWithObjectsAndKeys:(id)firstObject, , ...

  NSDictionary *dic1 = [[NSDictionary alloc] initWithObjectsAndKeys:@"zhgds",@"name",@20,@"hight",@12,@"age",nil];
  NSLog(@"%@",dic1);

3.求字典中元素的个数 count Returns the number of entries in the dictionary.

• (NSUInteger)count
  NSLog(@"%lu",[dic count]);
  4.获取字典中所有key Returns a new array containing the dictionary’s keys.
• (NSArray *)allKeys 注意返回值为一个数组

NSArray *keys = [dic allKeys];

    NSLog(@"%@",keys); 

5.objectForKey 根据key获取对应的value 根据对象取值 类型一定要匹配
NSString name = [dic objectForKey:@"name"];
NSLog(@"%@",name);
NSNumber age = [dic objectForKey:@"age"];
NSLog(@"%@",age);
NSNumber *hight = [dic objectForKey:@"hight"];
NSLog(@"%@",hight);

1. 快速遍历 对于数组来说遍历到的是数组中的元素 对于字典来时遍历到的是key 一个key对应一个value 但value可以对应多个key
   for (NSString *k in dic) {
   //检索到key之后获取对应的value.
   NSLog(@"%@",[dic objectForKey:k]);
   }

7.创建可变字典对象 NSMutableDictionary
1.创建对象的两种方式 便利构造器和初始化
NSMutableDictionary dic = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"xiaoguang",@"guanggun1",@"xiaoshuai",@"guanggun2",@"xiaomeng",@"guanggun3", nil];
NSLog(@"%@",dic);
NSMutableDictionary dic1 = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"xiaoguang",@"guanggun1",@"xiaoshuai",@"guanggun2",@"xiaomeng",@"guanggun3", nil];
NSLog(@"%@",dic1);

2.求字典元素个数 同样是 count 返回值是一个整形的数
NSLog(@"%lu",[dic count]);

3.删除元素 removeObjectForKey removeAllObjects
[dic removeObjectForKey:@"guanggun1"];
NSLog(@"%@",dic);
[dic removeAllObjects];
NSLog(@"%@",dic);
4.添加元素 setObject需要特别注意 这里用的是set方法
[dic setObject:@"chengjie" forKey:@"guanggun1"];
NSLog(@"%@",dic);

5.修改key对应的value
[dic setObject:@"xiaocun" forKey:@"guanggun1"];
NSLog(@"%@",dic);
setObject:forKey:工作原理:根据指定key查找字典中是否存在相同的,若果存在则修改对应的value ,若果不存在,在字典中添加一个元素key-value键值对.

6.快速遍历 对于数组来说遍历到的是数组中的元素 对于字典来时遍历到的是key 一个key对应一个value 但value可以对应多个key
for (NSString *k in dic) {
//检索到key之后获取对应的value.
NSLog(@"%@",[dic objectForKey:k]);
}

25.集 集合类 NSSet 不可变集合
1.创建集合对象 两种方法 便利构造器 初始化方法 输出规范 {(元素,号间隔)} setWithObjects initWithObjects
NSSet set1 = [NSSet setWithObjects:@"1",@"2",@"3",@"4",@"5",@"6", nil];
NSLog(@"%@",set1);
NSSet set = [[NSSet alloc] initWithObjects:@"1dghdaj",@"2",@"3hsdflds",@"4",@"5",@"6", nil];
NSLog(@"%@",set);

2.获取元素个数 count
NSLog(@"%lu",[set count]);

3.获取集合的某个元素
NSString *str = [set anyObject];
NSLog(@"%@",str);

    NSString *str1 = [set anyObject];
    NSLog(@"%@",str1);

    NSString *str2 = [set anyObject];
    NSLog(@"%@",str2);

    NSString *str3 = [set anyObject];
    NSLog(@"%@",str3);

获取原则 :怎么方便怎么获取 可能是随机 但以上三种输出结果都一样 也不是随机 具体理解请参考API文档
4.判断集合中是否包含某个元素 containsObject
BOOL isExist = [set containsObject:@"2"];
NSLog(@"isExist = %d",isExist);

5.可变集合 创建对象两种方式 便利构造器 初始化
1.便利构造器 setWithObjects
NSMutableSet *set1 = [NSMutableSet setWithObjects:@"1",@"2",@"3",@"4",@"5",@"6", nil];
NSLog(@"%@",set1);

2.初始化方法
NSMutableSet *set1 = [[NSMutableSet alloc] initWithObjects:@"1",@"2",@"3",@"4",@"5",@"6", nil];
NSLog(@"%@",set1);

2.添加元素到集合中 利用 addObject:添加对象
[set1 addObject:@"6"];
NSLog(@"%@",set1);

3.移除集合中的对象的方法 removeObject
[set1 removeObject:@"5"];
NSLog(@"%@",set1);

26.排序高级
针对对象的不同属性的实例方法进行排序
1.main.m文件里

import import "Person.h"

int main(int argc, const char argv[])
{
@autoreleasepool {
//创建四个对象
Person xiaoli = [[Person alloc]initWithName:@"xiaoli" age:18 height:172];
Person zhangsan = [[Person alloc] initWithName:@"zhangsan" age:20 height:175];
Person lisi = [[Person alloc] initWithName:@"lisi" age:21 height:168];
Person wangwu = [[Person alloc] initWithName:@"wangwu" age:24 height:182];
//将对象存入数组中.
NSArray arr = [NSArray arrayWithObjects:xiaoli,zhangsan,lisi,wangwu, nil];
//sortedArrayUsingSelector适用于升序排序以及系统自定义的类进行排序
//对数组对象按姓名升序排列
NSArray sortArrName =[arr sortedArrayUsingSelector:@selector(compareByName:)];
NSLog(@"%@",sortArrName);
//对数组对象按年龄升序排列
NSArray sortarrage = [arr sortedArrayUsingSelector:@selector(compareByAge:)];
NSLog(@"%@",sortarrage);
//对数组对象按身高升序排列
NSArray sortarrheight = [arr sortedArrayUsingSelector:@selector(compareByHeight:)];
NSLog(@"%@",sortarrheight);
//对数组对象按姓名降序排列
NSArray sortarrnameDesecending =[arr sortedArrayUsingSelector:@selector(compareByAge:)];
NSLog(@"%@",sortarrnameDesecending);
//对字符串数组进行排序
//block的排序方式适用于数组中的对象是系统类型时 并且是降序排列时
NSArray arr1 = [[NSArray alloc] initWithObjects:@"aa",@"bb",@"cc",@"dd",@"ee",@"ff", nil];
//1.对数组进行升序排序
NSArray sortArrAscending = [arr1 sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"%@",sortArrAscending);
//1.对数组进行降序排序
NSString sortArrDescending =[arr1 sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
//对block匿名函数实现,比较方法
//将id 转为NSString类型
NSString str1 = (NSString )obj1;
NSString str2 = (NSString *)obj2;
//2.字符串比较
return -[str1 compare:str2];
}];
NSLog(@"%@",sortArrDescending);
}
return 0;
}

Person.h文件里

import

@interface Person : NSObject
{
NSString *_name;// 姓名
NSInteger _age;//年龄
CGFloat _height;//身
}
//设置名字

• (void)setName:(NSString *)name;
  //访问名字
• (NSString *)getName;
  //设置年龄
• (void)setAge:(NSInteger)age;
  //访问年龄
• (NSInteger)getAge;
• (void)setHeight:(CGFloat)height;
• (CGFloat)getHeight;
  //初始化方法
• (id)description;
  //定义初始化方法
• (id)initWithName:(NSString *)name age:(NSInteger)age height:(CGFloat)height;
  //添加比较方法 compare NSComparisonResult枚举结果
• (NSComparisonResult)compareByAge:(Person *)anotherPerson;
• (NSComparisonResult)compareByHeight:(Person *)anotherPerson;
• (NSComparisonResult)compareByName:(Person *)anotherPerson;
• (NSComparisonResult)compareByNameDesecending:(Person *)anotherPerson;
  @end

Person .m 文件里

import "Person.h"

@implementation Person

pragma mark - setter and getter

//设置名字

• (void)setName:(NSString *)name{
  _name = name;
  }
  //访问名字
• (NSString *)getName{
  return _name;
  }
  //设置年龄
• (void)setAge:(NSInteger)age{
  _age = age;
  }
  //访问年龄
• (NSInteger)getAge{
  return _age;
  }
• (void)setHeight:(CGFloat)height{
  _height = height;
  }
• (CGFloat)getHeight{
  return _height;
  }
  pragma mark - override method
• (id)description{
  return [NSString stringWithFormat:@"name:%@,age:%ld,height:%g",_name,_age,_height];
  }
  pragma mark - init method
• (id)initWithName:(NSString *)name age:(NSInteger)age height:(CGFloat)height{
  self = [super init];
  if (self) {
  _name = name;
  _age = age;
  _height =height;
  }
  return self;
  }
  pragma mark - compare method

  //添加比较方法 compare NSComparisonResult枚举结果
  //比较年龄

• (NSComparisonResult)compareByAge:(Person *)anotherPerson{
  if ([self getAge] > [anotherPerson getAge]) {
  return NSOrderedDescending;//对应的是 1
  } else if ([self getAge] == [anotherPerson getAge]){
  return NSOrderedSame;//对应的是 0
  } else {
  return NSOrderedAscending;//对应的是 -1
  }
  }
  //比较身高
• (NSComparisonResult)compareByHeight:(Person *)anotherPerson{
  if ([self getHeight] > [anotherPerson getHeight]) {
  return NSOrderedDescending;//对应的是 1
  } else if ([self getHeight] == [anotherPerson getHeight]){
  return NSOrderedSame;//对应的是 0
  } else {
  return NSOrderedAscending;//对应的是 -1
  }
  }
• (NSComparisonResult)compareByName:(Person *)anotherPerson{
  return [[self getName] compare:[anotherPerson getName]];
  }
• (NSComparisonResult)compareByNameDesecending:(Person *)anotherPerson{
  return - [[self getName] compare:[anotherPerson getName]];
  }
  @end