Error writing to long value to file Objective-C - objective-c

Question

I'm trying to create 9 text files on my Desktop which are named by variable i in the for loop. Inside each text file I want to write a long value determined by my bigInt function. The long value must then be written in the file 1000 times before moving on to the next text file. But I keep getting the error: Incompatible pointer types sending 'NSString*' to parameter of type 'NSData*'
My Function:
long bigInt(int i){
long big = 99*(i*99);
long evenBigger = big*(big*(big*big));
return evenBigger;
}
My main method:
long use;
int x = 0;
for (int i = 1; i<10; i++) {
while (x < 1000) {
use = bigInt(i);
//[NSString stringWithFormat:#"%ld", use];
//NSString *content = #"Text to write to file";
NSString *path = [NSString stringWithFormat: # "/Users/ou_snaaksie/Desktop/%i.txt", i];
//NSData *fileContents = [use dataUsingEncoding:NSUTF8StringEncoding];
[[NSFileManager defaultManager] createFileAtPath:path contents:[NSString stringWithFormat:#"%ld", use] attributes:nil];
x++;
}
}

Answer 1

I think you need to pass NSData instead of NSString object to contents in createFileAtPath:contents:attributes: method or you can do something like below:
if (![[NSFileManager defaultManager] fileExistsAtPath:path]) {
[[NSFileManager defaultManager] createFileAtPath:path contents:nil attributes:nil];
}
[[string dataUsingEncoding:NSUTF8StringEncoding] writeToFile:path atomically:YES];

Answer 2

You are passing a string as contents when it requires NSData. You have to convert the string to NSData. Try this in the body of your while loop:
use = bigInt(i);
NSString* str = [NSString stringWithFormat:#"%ld", use];
NSData* data_contents = [str dataUsingEncoding:NSUTF8StringEncoding];
NSString *path = [NSString stringWithFormat: # "/tmp/%i.txt", i];
[data_contents writeToFile:path atomically:YES];
x++;