oc73--NSArray使用

Posted 2020-10-04 672530440

//
//  main.m
//  NSArray和NSString之间转换

#import <Foundation/Foundation.h>

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

    NSArray *arr = @[@"lnj", @"lmj", @"jjj"];
    // 需求: 用-将所有的姓名连接起来生成一个字符串
    
    // 1.定义一个可变字符串保存拼接之后的结果
    NSMutableString *strM = [NSMutableString string];
    // 2.遍历数组, 取出数组中的每一个元素, 将元素添加到可变字符串中
    for (NSString *str in arr) {
        [strM appendString:str];
        // 3.每次添加完毕之后再添加一个-
        [strM appendString:@"-"];
    }
    [strM deleteCharactersInRange:NSMakeRange(strM.length - 1, 1)];  //lnj-lmj-jjj
    NSLog(@"strM = %@", strM);
    
    
    NSString *str = [arr componentsJoinedByString:@"**"];
    NSLog(@"str = %@", str);//lnj**lmj**jjj
    
    
    // 通过一个字符串生成一个数组
    // 也叫做字符串切割
    NSString *str1 = @"lnj**lmj**jjj";
    NSArray *arr1 = [str1 componentsSeparatedByString:@"**"];
    NSLog(@"arr = %@", arr1);//(lnj,lmj,jjj)
    
    return 0;
}

//  main.m
//  NSArray文件读写

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

int main(int argc, const char * argv[]) {
    // 1.将数组写入到文件中
    NSArray *arr = @[@"lnj", @"lmj", @"jjj"];
    // 其实如果将一个数组写入到文件中之后, 本质是写入了一个XML文件
    // 在ios开发中一般情况下我们会将XML文件的扩展名保存为plist,xcode打开，
    
    BOOL flag = [arr writeToFile:@"/Users/mctc/Desktop/a.txt" atomically:YES];
    /*
     <?xml version="1.0" encoding="UTF-8"?>
     <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
     <plist version="1.0">
     <array>
     <string>lnj</string>
     <string>lmj</string>
     <string>jjj</string>
     </array>
     </plist>
     */
    flag = [arr writeToFile:@"/Users/mctc/Desktop/a.plist" atomically:YES];
    NSLog(@"flag = %i", flag);
    
    Person *p1 = [Person new];
    p1.age = 10;
    
    Person *p2 = [Person new];
    p2.age = 20;
    
    Person *p3 = [Person new];
    p3.age = 5;
    
    Person *p4 = [Person new];
    p4.age = 7;
    
    NSArray *arr1 = @[p1, p2, p3, p4];
//     注意:writeToFile只能写入数组中保存的元素都是Foundation框架中的类创建的对象, 如果保存的是自定义对象那么不能写入
    BOOL flag1 = [arr1 writeToFile:@"/Users/mctc/Desktop/a.plist" atomically:YES];
    NSLog(@"flag = %i", flag1);
    
    
    // 2.从文件中读取一个数组
    NSArray *newArray = [NSArray arrayWithContentsOfFile:@"/Users/mctc/Desktop/a.plist"];
    NSLog(@"%@", newArray);//(lnj,lmj,jjj)

    
    return 0;
}