Objective-C中NSArray的基本用法示例

nsarray的排序

+ (id)studentwithfirstname:(nsstring *)firstname lastname:(nsstring *)lastname{ 
     
    student *stu = [[student alloc] init]; 
     
    stu.firstname = firstname; 
    stu.lastname = lastname; 
     
    return stu; 
} 
 
+ (id)studentwithfirstname:(nsstring *)firstname lastname:(nsstring *)lastname bookname:(nsstring *)bookname{ 
 
    student *stu = [student studentwithfirstname:firstname lastname:lastname]; 
     
    stu.book = [book bookwithname:bookname]; 
     
    return stu; 
 
} 
 
- (nscomparisonresult)comparestudent:(student *)stu{ 
     
    nscomparisonresult result = [self.firstname compare:stu.firstname]; 
     
    if (result == nsorderedsame) { 
        result = [self.lastname compare:stu.lastname]; 
    } 
     
    return result; 
     
} 
 
- (nsstring *)description{  
  
    //return [nsstring stringwithformat:@" %@ %@ %@",self.firstname,self.lastname,self.book.name]; 
    return [nsstring stringwithformat:@" %@ %@ %@",self.firstname,self.lastname,_book.name]; 
} 
 
 
#pragma mark 3.nsarray排序1 
void arraysort1(){ 
     
    nsarray *array = [nsarray arraywithobjects:@"2",@"3",@"1",@"4", nil nil]; 
     
    // 指定系统自带规定的比较方法compare: 
    nsarray *array2 = [array sortedarrayusingselector:@selector(compare:)]; 
    nslog(@"%@",array2); 
     
} 
 
#pragma mark 3.nsarray排序2 
void arraysort2(){  
      
    student *stu1 = [student studentwithfirstname:@"hu" lastname:@"mingtao"]; 
    student *stu2 = [student studentwithfirstname:@"zhu" lastname:@"wenpeng"]; 
    student *stu3 = [student studentwithfirstname:@"zhao" lastname:@"weisong"]; 
    student *stu4 = [student studentwithfirstname:@"hu" lastname:@"junpeng"]; 
     
    nsarray *array = [nsarray arraywithobjects:stu1,stu2,stu3,stu4, nil nil]; 
     
    // 类似java中得compareto,自己定义比较方式,但是一定要实现compare方法 
    nsarray *array2 = [array sortedarrayusingselector:@selector(comparestudent:)]; 
     
    nslog(@"%@",array2); 
 
} 
 
#pragma mark 3.nsarray排序3-block排序 
void arraysort3(){ 
     
    student *stu1 = [student studentwithfirstname:@"hu" lastname:@"mingtao"]; 
    student *stu2 = [student studentwithfirstname:@"zhu" lastname:@"wenpeng"]; 
    student *stu3 = [student studentwithfirstname:@"zhao" lastname:@"weisong"]; 
    student *stu4 = [student studentwithfirstname:@"hu" lastname:@"junpeng"]; 
     
    nsarray *array = [nsarray arraywithobjects:stu1,stu2,stu3,stu4, nil nil]; 
     
    nsarray *array2 = [array sortedarrayusingcomparator:^nscomparisonresult(student *obj1, student *obj2) { 
        nscomparisonresult result = [obj1.firstname compare:obj2.firstname]; 
         
        if (result == nsorderedsame) { 
            result = [obj1.lastname compare:obj2.lastname]; 
        }  
          
        return result; 
    }]; 
     
    nslog(@"%@",array2); 
 
     
}  
 
#pragma mark 4.nsarray排序4-高级排序 
void arraysort4(){ 
     
    student *stu1 = [student studentwithfirstname:@"hu" lastname:@"mingtao" bookname:@"lianai"]; 
    student *stu2 = [student studentwithfirstname:@"zhu" lastname:@"wenpeng" bookname:@"tianshi"]; 
    student *stu3 = [student studentwithfirstname:@"zhao" lastname:@"weisong" bookname:@"love"]; 
    student *stu4 = [student studentwithfirstname:@"hu" lastname:@"junpeng" bookname:@"qingren"]; 
     
    nsarray *array = [nsarray arraywithobjects:stu1,stu2,stu3,stu4, nil nil]; 
     
    // 1.先按照书名进行排序 
    nssortdescriptor *booknamedesc = [nssortdescriptor sortdescriptorwithkey:@"book.name" ascending:yes]; 
    // 2.先按照姓进行排序 
    nssortdescriptor *firstnamedesc = [nssortdescriptor sortdescriptorwithkey:@"firstname" ascending:yes]; 
    // 3.先按照名进行排序 
    nssortdescriptor *lastnamedesc = [nssortdescriptor sortdescriptorwithkey:@"lastname" ascending:yes]; 
 
    nsarray *array2 = [array sortedarrayusingdescriptors:[nsarray arraywithobjects:booknamedesc,firstnamedesc,lastnamedesc, nil nil]]; 
     
    nslog(@"%@",array2);  
      
     
}

nsarray的一些用法
nsarray  只允许装oc对象，并且不能装空值，空代表数组元素的结束

#pragma mark - nsarray的基本用法
   // 创建一个空数组
      nsarray *array = [nsarray array];
   // 创建有一个元素的数组
      array = [nsarray arraywithobject:@"123"];
    // 创建有多个元素的数组
      array = [nsarray arraywithobjects:@"a",@"b",nil ];//不能装nil空指针，空值代表数组元素结束
    // 将一个数组赋值给一个数组
    + (instancetype)arraywitharray:(nsarray *)array;
    // 获取元素的个数
       int count = [array count]; //和 count = array.count; 相同，都是调用get方法
    // 是否包含一个元素
      - (bool)containsobject:(id)anobject;
    // 返回最后一个元素
       - (id) lastobject;
     // 获取index位置的元素
        - (id)objectatindex:(nsuinteger) index;
     // 获取元素的位置
        - (nsuinteger) indexofobject:(id)anobject;
     // 在range范围内查找元素的位置
        - (nsuinteger) indexofobject:(id)anobject inrange:(nsrange)range;
     // 比较两个集合内容是否相同
        - (bool) isequaltoarray:(nsarray *)otherarray;
     // 返回两个集合中第一个相同的对象元素
        - (id) firstobjectcommonwitharray:(nsarray *)otherarray;

#pragma mark - nsarray的高级用法
        //让集合里面的所有元素都执行aselector这个方法
           - (void)makeobjectsperformselector:(sel)aselector;
        //让集合里面的所有元素都执行aselector这个方法,给这个方法添加参数，但是只支持一个参数
           - (void)makeobjectsperformselector:(sel)aselector withobject:(id)argument
        //添加一个元素，返回一个新的nsarray（方法调用者本身没有发生变化）
           - (nsarray *)arraybyaddingobject:(id)anobject
       //添加otherarray的所有元素，返回一个新的nsarray（方法着本身没有改变）
           - (nsarray *) arraybyaddingobjectsfromarray:(nsarray *) otherarray;
       //截取range范围的数组
           - (nsarray *) subarraywithrange:(nsrenge)range;
      //用separator做拼接符，拼接成一个字符串
           - (nsstring *) componentsjoinedbystring:(nsstring *)separator
      //将nsarray持久化到文件中去
           - (bool) writetofile:(nsstring *)path atomically:(bool)useauxiliaryfile

#pragma mark - nsarray的遍历
     // 方法一：普通遍历(利用for循环)
       void arrayfor1(){
        nsarray *array = [nsarray arraywithobjects:@"1",@"2",@"3",nil];
        int count = array.count;
        for(int i=0; i<count; i++){
              id obj = [array objectatindex:i];
             nslog(@"%i-%@",i, obj);
        }
       }

     // 方法二：快速遍历
       void arrayfor2(){
           nsarray *array = [nsarray arraywithobjects:@"1",@"2",@"3",nil];
           int count = array.count;
           int i=0;
           for(id obj in array){
                nslog(@"%i-%@",i, obj);
                i++;
           }
         }

     // 方法三：利用block遍历
          void arrayfor3(){
               nsarray *array = [nsarray arraywithobjects:@"1",@"2",@"3",nil];
               [array enumerateobjectsusingblock:^(id obj, nsuinteger idx, bool *stop) {
                       nslog(@"%zi->%@",idx, obj);
                        //  *stop = yes; //改变外边的bool，终止遍历
                  }];
             }

    // 方法四：利用迭代器
 先介绍一下-->nsenumerator迭代器：集合的迭代器，可以用于遍历集合元素,nsarray 有相应的方法来获取迭代器
                  //获取一个正序遍历的迭代器
                     - (nsenumerator *) objectenumerator;
                 //获取一个反序遍历的迭代器
                     - (nsenumerator *) reverseobjectenumerator;
                @常用方法：
                 //获取下一个元素
                    - (id) nextobject;
                 //获取所有的元素
                    - (nsarray *) allobjects
          void arrayfor4(){
                   nsarray *array = [nsarray arraywithobjects:@"1",@"2",@"3",nil];
                   nsenumerator *enumerator = [array objectenumerator];// 返回数组的迭代器
                   //如果放到遍历之后，则取到空，原因是，遍历完了，就没值了
                   nsarray *array2 = [enumerator allobjects];
                   nslog(@"array2=%@", array2);
   
                 //获取下一个需要遍历的元素
                   id obj = nil;
                   while (obj = [enumerator nextobject]) {
                         nslog(@"obj=%@", obj);
                   }
                  }

使用block 块遍历整个数组。这个block 需要三个参数，id obj 表示数组中的元素。 
nsuinteger idx 标示元素的下标， 
boolbool *stop 是一个bool类型的参数。 官方描述如下： 
a reference to a boolean value. the block can set the value to yes to stop further processing of the array.  
the stop argument is an out-only argument. you should only ever set this boolean to yes within the block. 
- (void)enumerateobjectsusingblock:(void (^)(id obj, nsuinteger idx,boolbool *stop))block  
调用例子如： 
 

 
nsarray *array = [nsarray arraywithobjects:@"wendy",@"andy",@"tom",@"test", nil nil];  
  
  
   [array enumerateobjectsusingblock:^(id str,nsuinteger index, bool* te){ 
       nslog(@"%@,%d",str,index); 
   }]; 

同上面的方法一项，区别在于，这里多添加了一个参数，用来标示 是从前向后遍历，还是从后往前遍历。 
- (void)enumerateobjectswithoptions:(nsenumerationoptions)opts usingblock:(void (^)(id obj, nsuinteger idx,boolbool *stop))block 
调用例子如下： 

nsarray *array = [nsarray arraywithobjects:@"wendy",@"andy",@"tom",@"test", nil nil]; 
 
 
    [array enumerateobjectswithoptions:nsenumerationreverse usingblock:^(id str,nsuinteger index, bool* te){ 
        nslog(@"%@,%d",str,index);  
    }];