[英]Objective C - Create text file to read and write line by line in Cocoa
我構建一個Mac應用程序,我有2個問題:
- 我想創建一個文本文件來讀取和寫入數據。 我不知道如何創建文本文件以讀取和寫入數據。 它是否使用struct?
- 我想創建一個XML文件來讀取和寫入數據。 我可以為XML創建結構嗎?
你有什么建議嗎? 提前致謝
好吧,要創建一個文件,只需使用
[[NSFileManager defaultManager] createFileAtPath:@"Your/Path" contents:nil attributes:nil];
這會創建一個空文件,您可以寫入或讀取該文件。 要編寫文本(或XML),只需使用NSString
的writeToFile:atomically:encoding:error:
方法
NSString *str = //Your text or XML
[str writeToFile:"Your/Path" atomically:YES encoding:NSUTF8StringEncoding error:nil];
要從文件中讀取,只需使用該文件的內容創建一個NSString
NSString *contents = [NSString stringWithContentsOfFile:@"Your/Path"];
或者,如果它不包含字符串,則從文件中獲取NSData
對象
NSData *contents = [NSData dataWithContentsOfFile:@"Your/Path"];
/**************************main.m******************************
NS FILE HANDLE READ & WRITE
reading and writing in same file
Created by abdulsathar on 6/16/14.
***************************************************************/
#import <Foundation/Foundation.h>
int main(int argc, const char * argv[])
{
@autoreleasepool //ARC
{
NSFileHandle *file;
//object for File Handle
NSError *error;
//crearing error object for string with file contents format
NSMutableData *writingdatatofile;
//create mutable object for ns data
NSString *filePath=[NSString stringWithFormat:@"/Users/chandrakumar/Documents/abdul/doc.txt"];
//telling about File Path for Reading for easy of access
file = [NSFileHandle fileHandleForReadingAtPath:@"/Users/chandrakumar/Documents/abdul/doc.txt"];
//assign file path directory
if (file == nil) //check file exist or not
NSLog(@"Failed to open file");
NSString *getfileContents = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:&error];
//access file contents with out ns handle method
if (error) //check error flag for file present or not
NSLog(@"Error reading file: %@", error.localizedDescription);
NSLog(@"contents: %@", getfileContents);
//display file contents in main file
NSArray *listArray = [getfileContents componentsSeparatedByString:@"\n"];
//caluculate list of line present in files
NSLog(@"items = %ld", [listArray count]);
const char *writingchar = "how are you";
writingdatatofile = [NSMutableData dataWithBytes:writingchar length:strlen(writingchar)];
//convert string format into ns mutable data format
file = [NSFileHandle fileHandleForUpdatingAtPath: @"/Users/chandrakumar/Documents/abdul/new.txt"];
//set writing path to file
if (file == nil) //check file present or not in file
NSLog(@"Failed to open file");
[file seekToFileOffset: 6];
//object pointer initialy points the offset as 6 position in file
[file writeData: writingdatatofile];
//writing data to new file
[file closeFile];
//close the file
}
return 0;`enter code here`
}
/***********************************OUTPUT********************************************
2014-06-17 14:55:39.695 storage[4075:303] contents: hello how are you my dearservice
*************************************************************************************/
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