//
//  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-jjjNSLog(@"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;
}