Objective-C：Foundation框架-常用类-NSArray
2024-10-14 02:27:40
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);
}
最新文章
- scrollView的讲解
- iOS,文本输入,键盘相关
- MVC学习地址
- linux下vi操作出现E325: ATTENTION的解决方法
- 往Android SDCard中读写入数据
- poj 2891 Strange Way to Express Integers (扩展gcd)
- [设计模式]<<设计模式之禅>>关于里氏替换原则
- 第十二篇、HTML常用框架收集
- Java读取文件夹大小的6种方法及代码
- group By 和 Union 、 Union all的用法
- Eclipse下如何打开ftl文件
- USACO Arithmetic Progressions 【构造等差数列】
- JSP基本语法--实例演练
- Django中url使用命名空间的错误
- Redis详解（一）------ redis的简介与安装
- sprigmvc 传值jsp页面
- 6.MongoDB4.0在Windows环境的下载、安装、配置
- 关于vue中钩子函数非常好的博客
- python的Web框架，会话保持及Form表单
- pageContext中page、request、session、application四种范围变量的用法。