NSFileHandle编写json数据格式

+ (void)writeToFile:(NSDictionary *)params filePath:(NSString *)path {
NSData *jsonData = [self jsonToData:params];

NSFileHandle *fileHandle = [NSFileHandle fileHandleForUpdatingAtPath:path];
if (fileHandle == nil) {
NSLog(@"Failed to open file");
}

// 获取文件内容末尾的']'
[fileHandle seekToFileOffset:[fileHandle seekToEndOfFile] - 1];
NSData *endData = [fileHandle readDataToEndOfFile];

// 插入params
[fileHandle seekToFileOffset:[fileHandle seekToEndOfFile] - 1];
[fileHandle writeData:jsonData];

// 数组数据分割符
NSData *diviData = [@"," dataUsingEncoding:NSUTF8StringEncoding];
[fileHandle seekToEndOfFile];
[fileHandle writeData:diviData];

// 在文件内容末尾添加结束标识符']'
[fileHandle seekToEndOfFile];
[fileHandle writeData:endData];

//关闭文件
[fileHandle closeFile];
}