http://blog.****.net/daiyelang/article/details/18726947
1.创建数组
- // 创建一个空的数组
- NSArray *array = [NSArray array];
- // 创建有1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", @"c", nil nil];
- NSArray *array3 = [array arrayByAddingObjectsFromArray:[NSArray arrayWithObjects:@"4", @"5", nil nil]];
- NSArray *array4 = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil nil];
- NSRange range = NSMakeRange(1, 2);
- NSArray *array5 = [array4 subarrayWithRange:range];
2.数组的一些基本方法
- int count = [array count];//个数
- // 判断是否包含了某个元素
- if ([array containsObject:@"a"]) {
- NSLog(@"包含了字符串a");
- }
- NSString *last = [array lastObject];最后一个元素
- NSString *str = [array objectAtIndex:1];根据索引获取数组中的元素
- int index = [array indexOfObject:@"c"];获取指定元素的索引
- // 让数组里面的所有对象都调用test方法,123为参数
- NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil nil];
- [array makeObjectsPerformSelector:@selector(test2:) withObject:@"123"];
- NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil nil];
- // 1-2-3-4
- // 利用分隔符-拼接所有的数组元素
- NSString *str = [array componentsJoinedByString:@"-"];
- // 将一个数组写入文件(生成的是一个xml文件)
- NSString *path = @"/Users/apple/Desktop/array.xml";
- [array writeToFile:path atomically:YES];
- path = @"/Users/apple/Desktop/array.txt";
- // 从文件中读取数组内容(文件有严格的格式要求)
- NSArray *array2 = [NSArray arrayWithContentsOfFile:path];
3.遍历数组
- #pragma mark 遍历数组1
- void arrayFor1() {
- NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];
- int count = array.count;
- for (int i = 0; i<count; i++) {
- id obj = [array objectAtIndex:i];
- }
- }
- #pragma mark 遍历数组2 快速遍历
- void arrayFor2() {
- Student *stu1 = [Student student];
- NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];
- int i =0;
- for (id obj in array) {
- NSLog(@"%i-%@", i, obj);
- i++;
- }
- }
- #pragma mark 遍历数组3
- void arrayFor3() {
- Student *stu1 = [Student student];
- NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];
- [array enumerateObjectsUsingBlock:
- ^(id obj, NSUInteger idx, BOOLBOOL *stop) {
- NSLog(@"%i-%@", idx, obj);
- // 如果索引为1,就停止遍历
- if (idx == 1) {
- // 利用指针修改外面BOOL变量的值
- *stop = YES;
- }
- }];
- }
- #pragma mark 遍历数组4
- void arrayFor4() {
- Student *stu1 = [Student student];
- NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];
- // 获取数组的迭代器
- // NSEnumerator *enumerator = [array objectEnumerator];
- // 反序迭代器(从尾部开始遍历元素)
- NSEnumerator *enumerator = [array reverseObjectEnumerator];
- // allObjects是取出没有被遍历过的对象
- 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);
- }
- }
4.数组排序
- #pragma mark 数组排序1
- void arraySort1() {
- NSArray *array = [NSArray arrayWithObjects:@"2", @"3", @"1", @"4", nil nil];
- // 返回一个排好序的数组,原来数组的元素顺序不会改变
- // 指定元素的比较方法:compare:
- NSArray *array2 = [array sortedArrayUsingSelector:@selector(compare:)];
- NSLog(@"array2:%@", array2);
- }
- #pragma mark 数组排序2
- void arraySort2() {
- Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li"];
- Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang"];
- Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li"];
- Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao"];
- NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];
- // 指定排序的比较方法
- NSArray *array2 = [array sortedArrayUsingSelector:@selector(compareStudent:)];
- NSLog(@"array2:%@", array2);
- }
- - (NSComparisonResult)compareStudent:(Student *)stu {
- // 先按照姓排序
- NSComparisonResult result = [self.lastname compare:stu.lastname];
- // 如果有相同的姓,就比较名字
- if (result == NSOrderedSame) {
- result = [self.firstname compare:stu.firstname];
- }
- return result;
- }
- #pragma mark 数组排序3
- void arraySort3() {
- Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li"];
- Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang"];
- Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li"];
- Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao"];
- NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];
- // 利用block进行排序
- NSArray *array2 = [array sortedArrayUsingComparator:
- ^NSComparisonResult(Student *obj1, Student *obj2) {
- // 先按照姓排序
- NSComparisonResult result = [obj1.lastname compare:obj2.lastname];
- // 如果有相同的姓,就比较名字
- if (result == NSOrderedSame) {
- result = [obj1.firstname compare:obj2.firstname];
- }
- return result;
- }];
- NSLog(@"array2:%@", array2);
- }
- #pragma mark 数组排序4-高级排序
- void arraySort4() {
- Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li" bookName:@"book1"];
- Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang" bookName:@"book2"];
- Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li" bookName:@"book2"];
- Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao" bookName:@"book1"];
- NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];
- // 1.先按照书名进行排序
- // 这里的key写的是@property的名称
- NSSortDescriptor *bookNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"book.name" ascending:YES];
- // 2.再按照姓进行排序
- NSSortDescriptor *lastnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"lastname" ascending:YES];
- // 3.再按照名进行排序
- NSSortDescriptor *firstnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"firstname" ascending:YES];
- // 按顺序添加排序描述器
- NSArray *descs = [NSArray arrayWithObjects:bookNameDesc, lastnameDesc, firstnameDesc, nil nil];
- NSArray *array2 = [array sortedArrayUsingDescriptors:descs];
- NSLog(@"array2:%@", array2);
- }