oc70--NSArray1

Posted 2020-10-04 672530440

//
//  main.m
//  NSArray是不可变的，一旦初始化完毕，就不能添加和删除了。类似于NSString和NSMutilString。

#import <Foundation/Foundation.h>
#import "Person.h"

int main(int argc, const char * argv[]) {

    NSArray *arr1 = [[NSArray alloc] init]; //NSArray是不可变的，这样创建空的数组，以后又不能修改，所以这是没用的。
    NSArray *arr2 = [NSArray arrayWithObject:@"lnj"];
    // 数组中的nil是结束符
    NSArray *arr3 = [NSArray arrayWithObjects:@"lnj", @"lmj" ,@"jjj", @"cp", nil];
    NSLog(@"%@", arr3);//(lnj,lmj,jjj,cp),圆括号就是数组。
    
    Person *p  = [Person new];
    NSObject *obj = [NSObject new];
    //+ (instancetype)arrayWithObjects:(ObjectType)firstObj, ... NS_REQUIRES_NIL_TERMINATION;  ...表示是可变参数。
    NSArray *arr4 = [NSArray arrayWithObjects:p, obj, @"lnj", nil];//nil是一个结束符
    NSLog(@"arr = %@", arr4);//("<Person: 0x100304790>","<NSObject: 0x1007003b0>",lnj)
    NSLog(@"count = %lu", [arr4 count]);//3
    NSLog(@"last = %@", [arr4 lastObject]);//lnj
    NSLog(@"first = %@", [arr4 firstObject]);//<Person: 0x100304790>
    NSLog(@"arr[1] = %@", [arr4 objectAtIndex:1]);//<NSObject: 0x1007003b0>
    
    NSArray *arr5 = [NSArray arrayWithObjects:@"lnj", @"lmj", @"jjj", @"zs", nil];
    if([arr5 containsObject:@"zs"])
    {
        NSLog(@"arr中包含zs");
    }else
    {
        NSLog(@"arr中不包含zs");
    }
    
    // 创建数组简写
    NSString *str = @"lnj";
    NSArray *arr6 = [NSArray arrayWithObjects:@"lnj", @"lmj", @"jjj", nil];
    NSArray *arr7 = @[@"lnj", @"lmj", @"jjj"];
    // 获取数组元素的简写
    NSLog(@"%@", [arr7 objectAtIndex:0]);
    NSLog(@"%@", arr7[0]);
    return 0;
}