iOS - OC NSArray 数组

时间 2019-11-13

标签 ios nsarray 数组栏目 iOS 繁體版

原文原文链接

前言

@interface NSArray<__covariant ObjectType> : NSObject <NSCopying, NSMutableCopying, NSSecureCoding, NSFastEnumeration>
    @interface NSMutableArray<ObjectType> : NSArray<ObjectType>

数组只能存储 OC 对象，不能存储 C 语言中的基本数据类型，也不能存储 nil 。数组
Xcode 7 对系统中经常使用的一系列容器类型都增长了泛型支持（），有了泛型后就能够指定容器类中对象的类型了。假如向泛型容器中加入错误的对象，编译器会报警告。 atom
```
__covariant：协变性，子类型能够强转到父类型（里氏替换原则）。
    __contravariant：逆变性，父类型能够强转到子类型。
```
不指定泛型类型的对象能够和任意泛型类型转化，但指定了泛型类型后，两个不一样类型间是不能够强转的，假如你但愿主动控制转化关系，就须要使用泛型的协变性和逆变性修饰符。url

一、不可变数组 NSArray 的建立

// 直接建立不可变数组
    /*
        数组成员是 id 类型，表示数组元素能够是任意的 oc 对象。
    */
    NSArray *arr1 = @[@"bei", @"jing", @"huan", @"ying", @"nin"];
        
    // 对象方法建立
            
        NSArray *arr2 = [[NSArray alloc] init];
            
        // 和 arr1 的地址不相同
        NSArray *arr3 = [[NSArray alloc] initWithArray:arr1];
            
        NSArray *arr4 = [[NSArray alloc] initWithObjects:@"bei", @"jing", @"huan", @"ying", @"nin", nil];
            
    // 类方法建立
    
        NSArray *arr5 = [NSArray array];
        
        // 和 arr1 的地址不相同
        NSArray *arr6 = [NSArray arrayWithArray:arr1];
        
        // 建立只有一个元素(id)的数组
        NSArray *arr7 = [NSArray arrayWithObject:@"qian"];
                                                         
        NSArray *arr8 = [NSArray arrayWithObjects:@"bei", @"jing", @"huan", @"ying", @"nin", nil];
            
    // 从 文件 建立字符串
    NSString *path = [NSHomeDirectory() stringByAppendingString:@"/Desktop/test.txt"];
        
    NSArray *arr9 = [[NSArray alloc] initWithContentsOfFile:path];
    NSArray *arr10 = [NSArray arrayWithContentsOfFile:path];
        
    // 从 Url 建立字符串
    /*
        file:// 文件前缀
    */
    NSURL *url = [NSURL URLWithString:[@"file://" stringByAppendingString:[NSHomeDirectory() 
                                                  stringByAppendingString:@"/Desktop/test.txt"]]];
    
    NSArray *arr11 = [[NSArray alloc] initWithContentsOfURL:url];
    NSArray *arr12 = [NSArray arrayWithContentsOfURL:url];
        
    // 泛型定义
        
        // 指明数组中存放的是 NSString 类型数据
        NSArray<NSString *> *arr13 = @[@"bei", @"jing", @"huan", @"ying", @"nin"];
        
        // 指明数组中存放的是 NSNumber 类型数据
        NSArray<NSNumber *> *arr14 = @[@2, @4, @6, @8, @10];

二、数组成员个数计算

NSArray *arr = @[@"bei", @"jing", @"huan", @"ying", @"nin"];
        
    NSUInteger length = [arr count];

三、从数组中取成员

NSArray *arr = @[@"bei", @"jing", @"huan", @"ying", @"nin"];
        
    // []
    NSArray *arr1 = arr[1];
        
    // objectAtIndex
    NSArray *arr2 = [arr objectAtIndex:2];
        
    // subarrayWithRange
    NSArray *arr3 = [arr subarrayWithRange:NSMakeRange(2, 2)];
        
    // for...in 循环
    /*
        取出数组中的每一个元素，分别保存在 tmp 中
    */
    for (NSString *tmp in arr) {
    
        NSLog(@"%@", tmp);
    }
        
    // id (void *) 泛型指针， 取出数组中的每一个元素，分别保存在 tmp 中
    for (id tmp in arr) {
    
        NSLog(@"tmp = %@", tmp);
    }

四、取数组中最后一个元素

NSArray *arr = @[@"bei", @"jing", @"huan", @"ying", @"nin"];
        
    id lastObject1 = [arr lastObject];
        
    id lastObject2 = arr[[arr count]-1];

五、由元素的值获取下标

NSArray *arr = @[@"bei", @"jing", @"huan", @"ying", @"nin"];
        
    NSUInteger index = [arr indexOfObject:@"huan"];

六、判断数组中是否包含某个元素

NSArray *arr = @[@"bei", @"jing", @"huan", @"ying", @"nin"];
        
    BOOL result = [arr containsObject:@"huan"];

七、数组的比较

NSArray *arr1 = @[@"bei", @"jing", @"huan", @"ying", @"nin"];
    NSArray *arr2 = @[@"ni", @"hao", @"bei", @"jing"];
        
    // isEqualToArray
        
    // 比较两个数组内容是否相同
    BOOL bl = [arr1 isEqualToArray:arr2];
        
    // firstObjectCommonWithArray
        
    // 返回两个数组中第一个相同的元素
    NSString *str = [arr1 firstObjectCommonWithArray:arr2];

八、数组组合

NSArray *arr1 = @[@"bei", @"jing", @"huan", @"ying", @"nin"];
    NSArray *arr2 = @[@"Users", @"JHQ0228", @"Desktop"];
        
    // 按指定字符组合
    NSString *str1 = [arr1 componentsJoinedByString:@" "];
        
    // 按路径组合
    /*
        将数组中的元素自动组合成路径，在每一个元素之间自动加上 “／”
    */
    NSString *str2 = [NSString pathWithComponents:arr2];

九、可变数组 NSMutableArray 的建立

// 对象方法建立
    /*
        建立指定长度的数组，预先分配空间，提升效率，实际长度可大于指定长度
    */
    NSMutableArray *arr1 = [[NSMutableArray alloc] initWithCapacity:0];
        
    // 类方法建立
    /*
        建立指定长度的数组，预先分配空间，提升效率，实际长度可大于指定长度
    */
    NSMutableArray *arr2 = [NSMutableArray arrayWithCapacity:0];

十、数组元素的添加

NSMutableArray *arr = [NSMutableArray arrayWithCapacity:0];
        
    // addObject
        
        // 向数组中追加一个元素
        [arr addObject:@"bei"];
            
    // addObjectsFromArray
        
        // 追加数组
        NSArray *arrAdd = @[@"dian", @"ying", @"xue", @"yuan"];
        [arr addObjectsFromArray:arrAdd];
            
    // insertObject... atIndex
        
        // 在数组中任意位置插入一个元素
        [arr insertObject:@"hao" atIndex:2];
        
    // arrayByAddingObject
        
        // 向数组添加一个元素，返回一个新的数组
        NSArray *arr1 = [arr arrayByAddingObject:@"ma"];

十一、数组元素的删除

NSMutableArray *arr = [NSMutableArray arrayWithObjects:@"nan", @"jing", @"huan", @"ying", 
                                                           @"nin", @"bei", @"jing", @"ni", @"hao", nil];
        
    // 删除指定下标的元素
    [arr removeObjectAtIndex:2];
    
    // 删除指定元素，删除全部指定元素
    [arr removeObject:@"ying"];
    
    // 删除指定元素
    [arr removeObjectIdenticalTo:@"nan"];
    
    // 删除指定范围的元素
    NSRange range = {2,1};
    [arr removeObjectsInRange:range];
    
    // 删除最后一个元素
    [arr removeLastObject];
    
    // 删除全部元素
    [arr removeAllObjects];

十二、数组元素的替换

NSMutableArray *arr = [NSMutableArray arrayWithObjects:@"nan", @"jing", @"hao", nil];
        
    // 替换指定下标元素
    [arr replaceObjectAtIndex:1 withObject:@"ren"];

1三、数组元素的交换

NSMutableArray *arr = [NSMutableArray arrayWithObjects:@"bei", @"jing", @"nin", @"hao", nil];
        
    [arr exchangeObjectAtIndex:0 withObjectAtIndex:1];

1四、数组元素的修改

NSMutableArray *arr = [NSMutableArray arrayWithObjects:@"bei", @"jing", @"nin", @"hao", nil];
     
    // 修改整个数组（覆盖重写）
    [arr setArray:@[@"bei", @"jing", @"huan", @"ying",  @"nin"]];
    
    // 修改数组中的某个元素
    arr[3] = @"huan";

1五、给数组里的全部元素发送一个消息

Student *stu1 = [[Student alloc] init];
    Student *stu2 = [[Student alloc] init];
    Student *stu3 = [[Student alloc] init];
        
    NSArray *arr = [NSArray arrayWithObjects:stu1, stu2, stu3, nil];
        
    // 发送消息
    [arr makeObjectsPerformSelector:@selector(studentTest)];

1六、数组的遍历

用 for 循环遍历指针

NSArray * array = [NSArray arrayWithObjects:@"bei", @"jing", @"huan", @"ying", @"nin", nil];

    for (int i = 0; i < [array count]; i ++) {

        NSLog(@"%@", array[i]);
    }

用 for...in 循环遍历code

NSArray *array = [NSArray arrayWithObjects:@"bei", @"jing", @"huan", @"ying", @"nin", nil];

    // id (void *) 泛型指针， 取出数组中的每一个元素，分别保存在 tmp 中
    for (id tmp in array) {

        NSLog(@"%@", tmp);
    }

    // 取出数组中的每一个元素，分别保存在 tmp 中
    for (NSString *tmp in array) {

        NSLog(@"%@", tmp);
    }

用 block 循环遍历component

NSArray *array = [NSArray arrayWithObjects:@"bei", @"jing", @"huan", @"ying", @"nin", nil];

    [array enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {

        // obj == array[i]，idx == i
        NSLog(@"%@", obj);

        if ([obj  isEqual: @"huan"]) {

            // 中止遍历
            *stop = YES;
        }
    }];

用迭代器遍历orm

NSArray *array = [NSArray arrayWithObjects:@"bei", @"jing", @"huan", @"ying", @"nin", nil];

    // 获取数组的正序迭代器
    NSEnumerator *enu1 = [array objectEnumerator];

    // 获取数组的反序迭代器
    NSEnumerator *enu2 = [array reverseObjectEnumerator];

    id obj = nil;

    // 正序，获取下一个须要遍历的元素
    while (obj = [enu1 nextObject]) {

        NSLog(@"%@", obj);
    }

    // 反序，获取下一个须要遍历的元素
    while (obj = [enu2 nextObject]) {

        NSLog(@"%@", obj);
    }

条件遍历对象

// 1.indexesOfObjectsPassingTest

        NSArray *array = [NSArray arrayWithObjects:@3, @8, @17, @2, @25, @6, @89, nil];

        NSIndexSet *indexSet = [array indexesOfObjectsPassingTest:^BOOL(id  _Nonnull obj, 
                                                                          NSUInteger idx, 
                                                                     BOOL * _Nonnull stop) {

            // 遍历数组，找出数组中全部大于 10 的元素的位置
            return [obj intValue] > 10 ? : NO;
        }];

        [indexSet enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL * _Nonnull stop) {

            // 输出全部大于 10 的元素值
            NSLog(@"%@", array[idx]);
        }];

    // 2.indexOfObjectPassingTest

        NSUInteger index = [array indexOfObjectPassingTest:^BOOL(id  _Nonnull obj, 
                                                                   NSUInteger idx, 
                                                              BOOL * _Nonnull stop) {

            // 遍历数组，找出数组中第一个大于 10 的元素的位置
            return [obj intValue] > 10 ? : NO;
        }];

        // 输出第一个大于 10 的元素值
        NSLog(@"%@", array[index]);

1七、数组排序

冒泡排序排序

NSMutableArray *arr = [NSMutableArray arrayWithObjects:@"sunday", @"sunny", @"summer", @"sun", nil];

    for (int i = 0; i < [arr count] - 1; i++) {
        for (int j = 0; j < [arr count] - 1 - i; j++) {

            // 大小判断 arr[j] > arr[j + 1]
            if ([arr[j] compare:arr[j + 1]] == NSOrderedDescending) {

                // 位置交换
                [arr exchangeObjectAtIndex:j withObjectAtIndex:(j + 1)];
            }
        }
    }

用指定的方法排序ip

// 1.用指定的方法排序，可变数组排序

        NSMutableArray *arr1 = [NSMutableArray arrayWithObjects:@"sunday", @"sunny", @"summer", @"sun", nil];

        // 原数组的顺序改变，指定元素的比较方法：compare:，默认排序方式为升序排列
        [arr1 sortUsingSelector:@selector(compare:)];

        // 使排序结果 降序 排列
        NSEnumerator *enu = [arr1 reverseObjectEnumerator];

        id obj = nil;
        while (obj = [enu nextObject]) {

            // 排序后的结果为降序
            NSLog(@"%@", obj);
        }

    // 2.用指定的方法排序，不可变数组排序

        NSArray *arr2 = [NSArray arrayWithObjects:@"sunday", @"sunny", @"summer", @"sun", nil];

        // 返回一个排好的数组，原数组的顺序不变，指定元素的比较方法：compare:
        NSArray *arr3 = [arr2 sortedArrayUsingSelector:@selector(compare:)];

    // 3.用指定的方法排序，自定义类

        //  People.h

            #import <Foundation/Foundation.h>

            @interface People : NSObject

            // 名
            @property (nonatomic, retain) NSString *firstname;

            // 姓
            @property (nonatomic, retain) NSString *lastname;

            + (id)peopleWithFirstname:(NSString *)firstname lastname:(NSString *)lastname;

            // 返回值类型为 NSComparisonResult
            - (NSComparisonResult)comparePeople:(People *)peop;

            @end

        //  People.m

            #import "People.h"

            @implementation People

            + (id)peopleWithFirstname:(NSString *)firstname lastname:(NSString *)lastname {
                People * peop = [[People alloc] init];

                peop.lastname = lastname;
                peop.firstname = firstname;

                return peop;
            }

            - (NSComparisonResult)comparePeople:(People *)peop {

                // 先按照姓排序
                NSComparisonResult result = [self.lastname compare: peop.lastname];

                if (result == NSOrderedSame) {

                    // 若是有相同的姓，就比较名字
                    result = [self.firstname compare: peop.firstname];
                }

                return result;
            }

            -(NSString *)description{

                return [NSString stringWithFormat:@"%@ %@", self.firstname, self.lastname];
            }

            @end

        //  main.m

            #import "People.h"

            People *peop1 = [People peopleWithFirstname:@"MingJie" lastname:@"Li"];
            People *peop2 = [People peopleWithFirstname:@"LongHu" lastname:@"Huang"];
            People *peop3 = [People peopleWithFirstname:@"LianJie" lastname:@"Li"];
            People *peop4 = [People peopleWithFirstname:@"Jian" lastname:@"Xiao"];

            // 1.用指定的方法排序，可变数组排序

                NSMutableArray *array1 = [NSMutableArray arrayWithObjects:peop1, peop2, peop3, peop4, nil];

                // 原数组的顺序改变
                [array1 sortUsingSelector:@selector(comparePeople:)];

            // 2.用指定的方法排序，不可变数组排序

                NSArray *array2 = [NSArray arrayWithObjects:peop1, peop2, peop3, peop4, nil];

                // 返回一个排好的数组，原数组的顺序不变
                NSArray *array3 = [array2 sortedArrayUsingSelector:@selector(comparePeople:)];

用 Block 排序

// 1.利用 block 进行排序，可变数组排序

        NSMutableArray *arr1 = [NSMutableArray arrayWithObjects:@"sunday", @"sunny", @"summer", @"sun", nil];

        [arr1 sortUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {

            // 指定比较的方法，两个元素值比较
            NSComparisonResult result = [obj1 compare:obj2];

            // 返回比较的结果
            return result;
        }];

    // 2.利用 block 进行排序，不可变数组排序

        NSArray *arr2 = [NSArray arrayWithObjects:@"sunday", @"sunny", @"summer", @"sun", nil];

        // 返回一个排好的数组
        NSArray *arr3 = [arr2 sortedArrayUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {

            // 指定比较的方法，两个元素值比较
            NSComparisonResult result = [obj1 compare:obj2];

            // 返回比较的结果
            return result;
        }];

    // 3.利用 block 进行排序，自定义类

        // People1.h

            #import <Foundation/Foundation.h>

            @interface People1 : NSObject

            // 名
            @property (nonatomic, retain) NSString *firstname;

            // 姓
            @property (nonatomic, retain) NSString *lastname;

            + (id)peopleWithFirstname:(NSString *)firstname lastname:(NSString *)lastname;

            @end

        // People1.m

            #import "People1.h”

            @implementation People1

            + (id)peopleWithFirstname:(NSString *)firstname lastname:(NSString *)lastname {
                People1 * peop = [[People1 alloc] init];

                peop.lastname = lastname;
                peop.firstname = firstname;

                return peop;
            }

            -(NSString *)description{

                return [NSString stringWithFormat:@"%@ %@", self.firstname, self.lastname];
            }

            @end

        // main.m

            #import "People1.h”

            People1 *peop1 = [People1 peopleWithFirstname:@"MingJie" lastname:@"Li"];
            People1 *peop2 = [People1 peopleWithFirstname:@"LongHu" lastname:@"Huang"];
            People1 *peop3 = [People1 peopleWithFirstname:@"LianJie" lastname:@"Li"];
            People1 *peop4 = [People1 peopleWithFirstname:@"Jian" lastname:@"Xiao"];

            // 1.利用 block 进行排序，可变数组排序

                NSMutableArray *array1 = [NSMutableArray arrayWithObjects:peop1, peop2, peop3, peop4, nil];

                [array1 sortUsingComparator:^NSComparisonResult(People1 *  _Nonnull obj1, People1 *  _Nonnull obj2) {

                    // 先按照姓排序
                    NSComparisonResult result = [obj1.lastname compare:obj2.lastname];

                    if (result == NSOrderedSame) {

                        // 若是有相同的姓，就比较名字
                        result = [obj1.firstname compare:obj2.firstname];
                    }

                    return result;
                }];

            // 2.利用 block 进行排序，不可变数组排序

                NSArray *array2 = [NSArray arrayWithObjects:peop1, peop2, peop3, peop4, nil];

                NSArray *array3 = [array2 sortedArrayUsingComparator:^NSComparisonResult(People1 *  _Nonnull obj1, 
                                                                                         People1 *  _Nonnull obj2) {

                    // 先按照姓排序
                    NSComparisonResult result = [obj1.lastname compare:obj2.lastname];

                    if (result == NSOrderedSame) {

                        // 若是有相同的姓，就比较名字
                        result = [obj1.firstname compare:obj2.firstname];
                    }

                    return result;
                }];

按描述器排序

//  Book.h

        #import <Foundation/Foundation.h>

        @interface Book : NSObject

        @property (nonatomic, retain) NSString *name;

            + (id)bookWithName:(NSString *)name;

        @end

    //  Book.m

        #import "Book.h"

        @implementation Book

        + (id)bookWithName:(NSString *)name {
            Book *book = [[Book alloc] init];
            book.name = name;
            return book;
        }

        @end

    //  People2.h

        #import <Foundation/Foundation.h>

        @class Book;

        @interface People2 : NSObject

        // 名
        @property (nonatomic, retain) NSString *firstname;

        // 姓
        @property (nonatomic, retain) NSString *lastname;

        // 书
        @property (nonatomic, retain) Book *book;

        + (id)peopleWithFirstname:(NSString *)firstname lastname:(NSString *)lastname bookName:(NSString *)bookName;

        @end

    //  People2.m

        #import "People2.h"
        #import "Book.h"

        @implementation People2

        + (id)peopleWithFirstname:(NSString *)firstname lastname:(NSString *)lastname bookName:(NSString *)bookName {

            People2 *peop = [[People2 alloc] init];

            peop.lastname = lastname;
            peop.firstname = firstname;
            peop.book = [Book bookWithName:bookName];

            return peop;
        }

        - (NSString *)description{

            return [NSString stringWithFormat:@"%@ %@, bookName: %@", self.firstname, self.lastname, self.book.name];
        }

        @end

    // main.m

        #import "People2.h"

        People2 *peop1 = [People2 peopleWithFirstname:@"MingJie" lastname:@"Li" bookName:@"book1"];
        People2 *peop2 = [People2 peopleWithFirstname:@"LongHu" lastname:@"Huang" bookName:@"book2"];
        People2 *peop3 = [People2 peopleWithFirstname:@"LianJie" lastname:@"Li" bookName:@"book2"];
        People2 *peop4 = [People2 peopleWithFirstname:@"Jian" lastname:@"Xiao" bookName:@"book1"];

        // 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];

        // 再按照姓进行排序
        NSSortDescriptor *lastnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"lastname" ascending:YES];

        // 再按照名进行排序
        NSSortDescriptor *firstnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"firstname" ascending:YES];

        // 1.按描述器排序，可变数组排序

            NSMutableArray *array1 = [NSMutableArray arrayWithObjects:peop1, peop2, peop3, peop4, nil];

            // 按顺序添加排序描述器
            NSMutableArray *descs1 = [NSMutableArray arrayWithObjects:bookNameDesc, lastnameDesc, firstnameDesc, nil];

            [array1 sortUsingDescriptors:descs1];

        // 2.按描述器排序，不可变数组排序

            NSArray *array2 = [NSArray arrayWithObjects:peop1, peop2, peop3, peop4, nil];

            // 按顺序添加排序描述器
            NSArray *descs2 = [NSArray arrayWithObjects:bookNameDesc, lastnameDesc, firstnameDesc, nil];

            NSArray *array3 = [array2 sortedArrayUsingDescriptors:descs2];