iPhone开发之文件创建、删除、读取、写入

创建与删除：
//创建文件管理器
NSFileManager
*fileManager = [NSFileManager defaultManager];

//获取路径

//参数NSDocumentDirectory要获取那种路径
NSArray
*paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

NSString *documentsDirectory = [paths objectAtIndex:0];

//更改到待操作的目录下

[fileManager changeCurrentDirectoryPath:[documentsDirectory stringByExpandingTildeInPath]];

//创建文件fileName文件名称，contents文件的内容，如果开始没有内容可以设置为nil，attributes文件的属性，初始为nil
[fileManager
createFileAtPath:@"fileName" contents:nil attributes:nil];

//删除待删除的文件

[fileManager removeItemAtPath:@"createdNewFile" error:nil];

写入数据：
//获取文件路径
NSString
*path = [documentsDirectory stringByAppendingPathComponent:@"fileName"];

//待写入的数据
NSString
*temp = @”Welcome to blog.iosxcode4.com”;

int data0 = 100000;

float data1 = 23.45f;

//创建数据缓冲
NSMutableData
*writer = [[NSMutableData alloc] init];

//将字符串添加到缓冲中
[writer
appendData:[temp dataUsingEncoding:NSUTF8StringEncoding]];

//将其他数据添加到缓冲中
[writer
appendBytes:&data0 length:sizeof(data0)];

[writer appendBytes:&data1 length:sizeof(data1)];

//将缓冲的数据写入到文件中
[writer
writeToFile:path atomically:YES];

[writer release];

读取数据：
int
gData0;

float gData1;

NSString *gData2;

NSData *reader = [NSData dataWithContentsOfFile:path];

gData2 = [[NSString alloc] initWithData:[reader subdataWithRange:NSMakeRange(0, [temp length])]

encoding:NSUTF8StringEncoding];

[reader getBytes:&gData0 range:NSMakeRange([temp length], sizeof(gData0))];

[reader getBytes:&gData2 range:NSMakeRange([temp length] + sizeof(gData0), sizeof(gData1))];

NSLog(@”gData0:%@  gData1:%i gData2:%f”, gData0, gData1, gData2);