字符串的导出，写到某个文件中去
void stringExport(){
NSString *str=@"123456";
//if file not exist will not show error and it will create
//if file folder not exist will show error文件夹不存在
//if encoding not match will show error编码指定错误
NSString *path=@"/User/apple/Desktop/test.txt";
NSError *error;
//Will cover old content.
//atomically原子性。safer,123/456 if error temp will be delete and Text.txt will not be created
//
// 非原子性 only 123
//
[str writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:&error];
if(error){
NSLog(@"Failed, infor%@",[error localizedDescription]);//return main error infor
}else{
NSLog(@"Successful");
}
}