Objective-C:Foundation框架-常用类-NSArray
NSArray是用来存储对象的有序列表(NSSet是没有顺序的),它是不可变的。NSArray不能存储C语言中的基本数据类型,如int\float\enum\struct等,也不能存储nil。其用法如下:
- #pragma mark 创建一个数组
- void arrayCreate() {
- // 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:@""];
- // 创建有多个元素的数组
- array = [NSArray arrayWithObjects:@"a", @"b", @"c", nil];
- int count = [array count];
- // count = array.count;
- NSLog(@"%i", count);
- }
- #pragma mark 数组的简单使用
- void arrayUse() {
- NSObject *obj = [[NSObject alloc] init];
- NSArray *array = [NSArray arrayWithObjects:@"a", @"b", @"c" , obj, nil];
- // 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];
- NSLog(@"last=%@", last);
- NSString *str = [array objectAtIndex:];
- NSLog(@"%@", str);
- int index = [array indexOfObject:@"c"];
- NSLog(@"index=%i", index);
- [obj release];
- }
- #pragma mark 数组的内存管理
- void arrayMemory() {
- //
- Student *stu1 = [[Student alloc] init];
- Student *stu2 = [[Student alloc] init];
- Student *stu3 = [[Student alloc] init];
- NSLog(@"stu1:%zi", [stu1 retainCount]);
- // 当把一个对象塞进数组中时,这个对象的计数器会加1,也就是说数组会对它做一次retain操作
- //
- NSArray *array = [[NSArray alloc] initWithObjects:stu1, stu2, stu3, nil];
- NSLog(@"stu1:%zi", [stu1 retainCount]);
- NSLog(@"count=%zi", array.count);
- //
- [stu1 release];
- [stu2 release];
- [stu3 release];
- // 数组被销毁的时候,会对内部的所有元素都做一次release操作
- //
- [array release];
- }
- #pragma mark 给数组里面的元素发送消息
- void arrayMessage() {
- Student *stu1 = [Student student];
- Student *stu2 = [Student student];
- Student *stu3 = [Student student];
- NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil];
- // 让数组里面的所有对象都调用test方法
- // [array makeObjectsPerformSelector:@selector(test)];
- [array makeObjectsPerformSelector:@selector(test2:) withObject:@""];
- }
- #pragma mark 遍历数组1
- void arrayFor1() {
- Student *stu1 = [Student student];
- NSArray *array = [NSArray arrayWithObjects:stu1, @"", @"", @"", nil];
- int count = array.count;
- for (int i = ; i<count; i++) {
- // id == void *
- id obj = [array objectAtIndex:i];
- NSLog(@"%i-%@", i, obj);
- }
- }
- #pragma mark 遍历数组2
- void arrayFor2() {
- Student *stu1 = [Student student];
- NSArray *array = [NSArray arrayWithObjects:stu1, @"", @"", @"", nil];
- // 快速遍历
- int i =;
- 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, @"", @"", @"", nil];
- [array enumerateObjectsUsingBlock:
- ^(id obj, NSUInteger idx, BOOL *stop) {
- NSLog(@"%i-%@", idx, obj);
- // 如果索引为1,就停止遍历
- if (idx == ) {
- // 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, @"", @"", @"", 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);
- }
- }
- #import <Foundation/Foundation.h>
- @interface Book : NSObject
- @property (nonatomic, retain) NSString *name;
- + (id)bookWithName:(NSString *)name;
- @end
- #import "Book.h"
- @implementation Book
- + (id)bookWithName:(NSString *)name {
- Book *book = [[[Book alloc] init] autorelease];
- book.name = name;
- return book;
- }
- - (void)dealloc {
- [_name release];
- [super dealloc];
- }
- @end
- #pragma mark 派生出新的数组
- void arrayNew() {
- NSArray *array = [NSArray arrayWithObjects:@"", @"", nil];
- NSArray *array2 = [array arrayByAddingObject:@""];
- NSArray *array3 = [array arrayByAddingObjectsFromArray:[NSArray arrayWithObjects:@"", @"", nil]];
- NSLog(@"array:%@", array);
- NSLog(@"array2:%@", array2);
- NSLog(@"array3:%@", array3);
- NSArray *array4 = [NSArray arrayWithObjects:@"", @"", @"", @"", nil];
- NSRange range = NSMakeRange(, );
- NSArray *array5 = [array4 subarrayWithRange:range];
- NSLog(@"array5:%@", array5);
- }
- #pragma mark 数组的其他用法
- void arrayOther() {
- NSArray *array = [NSArray arrayWithObjects:@"", @"", @"", @"", nil];
- // 1-2-3-4
- // 利用分隔符-拼接所有的数组元素
- NSString *str = [array componentsJoinedByString:@"-"];
- NSLog(@"%@", str);
- // 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];
- NSLog(@"array2:%@", array2);
- }
- #pragma mark 数组排序1
- void arraySort1() {
- NSArray *array = [NSArray arrayWithObjects:@"", @"", @"", @"", 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];
- // 指定排序的比较方法
- NSArray *array2 = [array sortedArrayUsingSelector:@selector(compareStudent:)];
- NSLog(@"array2:%@", array2);
- }
- #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];
- // 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];
- // 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];
- NSArray *array2 = [array sortedArrayUsingDescriptors:descs];
- NSLog(@"array2:%@", array2);
- }
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