gistfile1.m

NSString *filename = [NSString stringWithFormat:@"%0.0f.png", [[NSDate date] timeIntervalSince1970]];
    
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
MSLogTo(@"info", @"documentsPath = %@",documentsPath);
NSURL *newUrl = [NSURL fileURLWithPath:documentsPath isDirectory:YES];
NSString *saveTo = [[newUrl absoluteString] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
MSLogTo(@"info", @"Saving image to %@",saveTo);
    
NSError *error;
if (![UIImagePNGRepresentation(image) writeToFile:saveTo options:NSDataWritingAtomic error:&error]) {
    MSLogTo(@"errors",@"Couldn't save image to documents: %@ <%@>",error,[error localizedDescription]);
    return;
}