iOS NSArray的属性

释放双眼,带上耳机,听听看~!

今天小编给大家详细解说一下Objective-C中NSArray的用法,感兴趣的朋友跟小编一起来了解一下吧!

NSArray的排序

复制代码 代码如下:

 

+ (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

  复制代码 代码如下:

  #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;>

  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:

  复制代码 代码如下:

  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:

  复制代码 代码如下:

  NSArray *array = [NSArray arrayWithObjects:@"wendy",@"andy",@"tom",@"test", nil nil];

  [array enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(id str,NSUInteger index, BOOL* te){

  NSLog(@"%@,%d",str,index);

  }];

 

以上就是iOS中NSArray的用法详解,想必都了解了吧,更多相关内容请继续关注技术狗。

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