IOS学习笔记2015-04-03OC-API-文件读写

////  WPFileHelper.m//  OC-API-文件操作////  Created by wangtouwang on 15/4/3.//  Copyright (c) 2015年 wangtouwang. All rights reserved.//#import "WPFileHelper.h"@implementation WPFileHelper+(NSString *)getFileToString:(int)tag{    NSString *result ;    //目标 读取字符型文件 例如后缀.txt    if (tag==0) {        //方法1 使用 NSString        NSError *error;        NSString *filePath =@"/Users/wangtouwang/Desktop/OC-控件.txt";        result = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:&error];        if (error) {            NSLog(@"read error ,the error is %@",error);        }else{            NSLog(@"read success,the file content is %@",result);        }    }else if (tag==1){        //方法2 使用  NSFileManager        NSString *filePath =@"/Users/wangtouwang/Desktop/OC-控件.txt";        NSFileManager *manager=[NSFileManager defaultManager];        NSData *data = [manager contentsAtPath:filePath];        result=  [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];        //NSLog(@"%@",result);    }else if (tag==2){        //方法3  NSFileHandle        NSString *filePath =@"/Users/wangtouwang/Desktop/OC-控件.txt";        NSFileHandle *handler = [NSFileHandle fileHandleForReadingAtPath:filePath];        NSData *data = [handler readDataToEndOfFile];        result=  [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];        [handler closeFile];        //NSLog(@"%@",result);    }else if(tag==3){        //方法4  NSData        NSString *filePath =@"/Users/wangtouwang/Desktop/OC-控件.txt";        //NSDataReadingMappedIfSafe参数。使用这个参数后，iOS就不会把整个文件全部读取的内存了，而是将文件映射到进程的地址空间中，        //这么做并不会占用实际内存。这样就可以解决内存满的问题。        NSData *data= [NSData dataWithContentsOfFile:filePath options:nil error:nil];        result =[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];       // NSLog(@"%@",result);    }    return result;}+(NSData *) getFileToData:(int)tag{    NSData *result = nil;    //目标 读取二进制文件 例如 图片    NSString *imagePath = @"/Users/wangtouwang/Desktop/TEMP/51sPBOtpQ0L._SL500_AA300_.jpg";    if (tag==0) {        // 方法1 NSData        result = [NSData dataWithContentsOfFile:imagePath];       // NSInteger len = result.length;        //NSLog(@"长度 = %lu",len);    }else if (tag == 1){        //方法2 NSFileHandle        NSFileHandle *handle = [NSFileHandle fileHandleForReadingAtPath:imagePath];       result =[handle readDataToEndOfFile];        [handle closeFile];        //方法3 NSFileManager    }else if(tag==2){        NSFileManager *manger = [NSFileManager defaultManager];       result = [manger contentsAtPath:imagePath];    }    return result;}+(void)writerFileByString:(NSString *)str{    NSString  *content = str;    NSString *filePath =@"/Users/wangtouwang/Desktop/新文件.txt";    // 写入字符型文件 例如后缀.txt 假如文件不存在依然成功    int tag =3;    if (tag==0) {        //方法1 NSString        [content writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];    }else if (tag==1){        //方法2  NSFileHandle 假如文件不存在会失败        NSData *data = [content dataUsingEncoding:NSUTF8StringEncoding];        NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:filePath];        [handle writeData:data];        [handle closeFile];    }else if(tag==2){        //方法3 NSFileManager 假如文件不存在依然成功        NSFileManager *manager = [NSFileManager defaultManager];        BOOL flag = [manager createFileAtPath:filePath contents:[content dataUsingEncoding:NSUTF8StringEncoding] attributes:nil];        if (flag) {            NSLog(@"写入成功");        }    }else if (tag==3){        //方法4  NSMutableData 假如文件不存在依然成功        NSMutableData *writer = [[NSMutableData alloc] init];        [writer appendData:[content dataUsingEncoding:NSUTF8StringEncoding]];        [writer writeToFile:filePath atomically:YES];    }}+(void)writerFileByData:(NSData *)data{    //写入二进制文件 例如图片    NSString *filePath =@"/Users/wangtouwang/Desktop/新文件.jpg";    int tag =2;    if (tag==0) {        //方法1 NSData        [data writeToFile:filePath atomically:YES];    }else if(tag==1){        //方法2 NSFileHanle 假如文件不存在则会失败,应该先判断是否存在,再看是否需要创建        NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:filePath];        [handle writeData:data];        [handle classCode];    }else if(tag==2){        //方法3 NSFileManager        NSFileManager *manager= [NSFileManager defaultManager];        [manager createFileAtPath:filePath contents:data attributes:nil];    }else if (tag==3){        // 方法4 NSMutableData        NSMutableData *writer = [[NSMutableData alloc] init];        [writer appendData:data];        [writer writeToFile:filePath atomically:YES];    }}@end