Question

Using Objective-C, how can I give/take the permissions for all user to read a file?

I need something that has the same effects as chmod a-r and chmod a+r.

Thank you!

Answer 1

Are you also familiar with the chmod 755 file method of changing permissions? using octal numbers?

NSMutableDictionary *dict = [[NSMutableDictionary alloc] init]; 

//Prefixing zero is octal.
int readPermission = 04;
int writePermission = 02;
int executePermission = 01;

//End multiplication is to shift digits left.
int owner = (readPermission | writePermission | executePermission) * (8 * 8);   //7
int group = (readPermission)                                       * (8);       //4 
int other = (executePermission);                                                //1

int permissions = owner + group + other;  //0741

[dict setObject:[NSNumber numberWithInt:permissions] forKey:NSFilePosixPermissions]; 

NSError *error = nil;
[[NSFileManager defaultManager] setAttributes:dict ofItemAtPath:[file path] error:&error];