Objective-C数组初识

1.数组的创建

OC中数组存储对象的地址

对象方法初始化

NSArray * arr1 = [[NSArray alloc] initWithObjects:@"one",@"two",@"three", nil];
        
NSLog(@"%@",arr1);

 类方法初始化

NSArray * arr2 = [NSArray arrayWithObjects:@"one",@"two",@"three", nil];

 

创建数组时以nil结束

使用@[]初始化

 NSArray * arr3 = @[@"one",@"two",@"three"]; 

 

2.数组存储基本数据类型 oc数组存储的是对象的地址 所以需要将基本数据类型的变量转变为对象的地址

numberWithInt:(int)   numberWithFloat:(float)   numberWithDouble:(double）

int age = 25;

NSNumber * num = [NSNumber numberWithInt:age];  

NSArray * arr5 = @[@"one",@"two",@"three",num];

NSLog(@"%@",arr5);

 3.数组中可以存放自定义对象

        Person * p1 = [[Person alloc] initWithName:@"Tom" andAge:18];
        Person * p2 = [[Person alloc] initWithName:@"Lilei" andAge:20];
        Person * p3 = [[Person alloc] initWithName:@"Lily" andAge:25];
        
        NSArray * arr6 = @[p1,p2,p3];        

#import <Foundation/Foundation.h>

@interface Person : NSObject {
    NSString * _name;
    int _age;
    
}
- (id)initWithName:(NSString *)name andAge:(int)age;
@end

#import "Person.h"

@implementation Person
- (id)initWithName:(NSString *)name andAge:(int)age {
    if (self = [super init]) {
        _name = name;
        _age = age;
    }
    return self;
}

- (NSString *)description {
    return [NSString stringWithFormat:@"name:%@ age:%d",_name,_age];
}

@end

- (NSString *)description； 该方法返回值即为打印数组时打印的字符串。

 

5.获取数组中的对象 

 Person * p4 = [arr6 objectAtIndex:2]; 2 NSLog(@"p4 %@",[p4 description]);  

6.获取数组中的个数

 NSUInteger count = [arr6 count]; 

 

7.判断是否包含元素

判断的是内容 而非地址 

        Person * p5 = [[Person alloc] initWithName:@"Jack" andAge:28];
        BOOL isContain = [arr6 containsObject:p5];
        
        if (isContain) {
            NSLog(@"包含");
        } else {
            NSLog(@"不包含");
        }
        
        NSString * str1 = [[NSString alloc] initWithFormat:@"one"];
        NSArray * arr7 = @[@"one",@"two",@"three"];
        BOOL isContain1 = [arr7 containsObject:str1];
        
        if (isContain1) {
            NSLog(@"包含");
        } else {
            NSLog(@"不包含");
        }

 

8.数组排序

        // @selector
        NSArray * arr = @[@"a",@"g",@"f",@"d",@"e"];
        
        // YES 左边 > 右边
        // 左边 < 右边
        BOOL isGreater = [@"b" isGreaterThan:@"a"];
        NSLog(@"isGreater %d",isGreater);
        
//        SEL sel = @selector(isGreaterThan:);
        NSLog(@"before %@",arr);
//        NSArray * arr2 = [arr sortedArrayUsingSelector:sel];
        NSArray * arr2 = [arr sortedArrayUsingSelector:@selector(isGreaterThan:)];
        NSLog(@"after %@",arr2);
        
        // @selector
        // Block
        // 声明: 返回值 (^名字)(参数列表) = ^返回值 (参数列表) {
    
//    }
        NSComparisonResult (^block)(id obj1,id obj2) = ^NSComparisonResult(id obj1, id obj2) {
            return [obj1 compare:obj2];
        };
        
        // Block
        NSArray * arr3 = [arr sortedArrayUsingComparator:block];
        
        [arr sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
            return [obj1 isLessThan:obj2];
        }];        
        NSLog(@"after arr3 %@",arr3);

@selector 传入一个方法名 也就是方法的地址  

Block

声明: 返回值 (^名字)(参数列表) = ^返回值 (参数列表) {

　　操作

}

 

9.可变数组

　　9.1 可变数组

NSArray * arr1 = @[@"one",@"two",@"three"];

NSMutableArray * muarr1 = [[NSMutableArray alloc] initWithArray:arr1];

NSMutableArray * muarr2 = [[NSMutableArray alloc] initWithObjects:@"one",@"two",@"three", nil];

　　NSMutableArray * muarr3 = @[@"one",@"two",@"three"];  并不能这样写

 

　　9.2重置数组 [muarr2 setArray:@[@"one"]]; 2 NSLog(@"%@",muarr2); 

　　9.3添加元素 [muarr2 addObject:@"two"];

        NSArray * arr2 = @[@"a",@"b",@"c"];
        // 把数组作为对象添加到数组中
        [muarr2 addObject:arr2];

 

　　9.4插入元素

        // 插入对象
        [muarr2 insertObject:@"z" atIndex:1];
         [muarr2 addObject:@"one"];
        NSLog(@"%@",muarr2);

　　9.5删除元素

        // 删除
        // 会通过对象地址,删除数组中所有的同一个地址的对象
        
        [muarr2 removeObject:@"one"];
        NSLog(@"%@",muarr2);
        
        // 删除 指定位置的对象
        [muarr2 removeObjectAtIndex:1];
        NSLog(@"%@",muarr2);
        // 删除全部对象
        [muarr2 removeAllObjects];
        NSLog(@"%@",muarr2);

 

 

10.遍历数组

[arr count]为数组的元素数

[arr objectAtIndex:i] 为index处的元素

        NSArray * arr = @[@"英雄联盟",@"跑跑卡丁车",@"红色警戒"];
        NSLog(@"%@",arr);
        
        NSString * str = arr[0];
        NSLog(@"%@",str);
        for (int i = 0; i < [arr count]; i++) {
            NSLog(@"%@",[arr objectAtIndex:i]);
        }
        // 快速枚举
        for (NSString * str in arr) {
            NSLog(@"%@",str);
        }

 

11.字符串与数组的相互转换

        NSString * str = @"I am a teacher";
        //componentsSeparatedByString: 用字符串来分割 用数组存储
        
        NSArray * arr = [str componentsSeparatedByString:@" "];
        NSLog(@"%@",arr);
        
        NSString * str2 = @"a";
        NSArray * arr1 = [str2 componentsSeparatedByString:@"a"];
        NSLog(@"%@",arr1);
        
        //componentsJoinedByString 用字符串拼接数组元素 范围一个新字符串
        NSString * str3 = [arr componentsJoinedByString:@"-"];
        NSLog(@"%@",str3);

 

附加 @selector语法

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSLog(@"%d",cal(3,5, add));
        
        Dog * dog = [[Dog alloc] init];
//        [dog bark];
        
        [dog eatAfterSel:@selector(rockTail)];
        
        
        
    }
    return 0;
}

#import <Foundation/Foundation.h>

@interface Dog : NSObject
- (void)bark;
- (void)rockTail;
- (void)eat;
- (void)eatAfterSel:(SEL)sel;

@end

#import "Dog.h"

@implementation Dog
- (void)bark {
    NSLog(@"wangwang");
}

- (void)rockTail {
    NSLog(@"狗在深情地摇着尾巴");
}

- (void)eat {
    NSLog(@"狗在吃屎");
}


- (void)eatAfterSel:(SEL)sel {
    [self performSelector:sel];
    [self eat];
}
@end