IOS基础知识记录六(读写文件)

NSString *filePath = @"/User/test.txt"
//判断文件是否存在, 否则创建该文件
if (![[NSFileManager alloc] fileExistsAtPath: filePath]) {
//contents 可以初始化文件时, 加入默认内容
[[NSFileManager alloc] createFileAtPath: filePath
contents: nil attributes: nil];
}

//更新文件
NSFileHandle *handler = [NSFileHandle fileHandleForUpdatingAtPath: filePath];
[handler seekToEndOfFile];//跳到文件末尾

NSString *content = @"this is a file."
[handler writeData: [content dataUsingEncoding: NSUTF8StringEncoding]];
[handler closeFile];

//读取文件
if ([[NSFileManager alloc] fileExistsAtPath: filePath]) {
NSFileHandle *handler = [NSFileHandle fileHandleForReadingAtPath: filePath];

//content读取的新内容
NSString *content = [[NSString alloc] initWithData: [handler availableData] encoding: NSUTF8StringEncoding];

[handler closeFile];
}

[handler closeFile];//文件读写后，关闭文件