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);
}];