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);
}];
