Please Select button in xib first. then select Attribute Inspector, in this Select Title in "Edge" and set appropriate "Inset" as per Requirements.
please take a look with below code and set insets as per your Requirements.
UIButton *myButton = [UIButton buttonWithType:UIButtonTypeCustom];
myButton.frame = CGRectMake(0, 0, self.view.bounds.size.width, 40);
[myButton setImage:[UIImage imageNamed:@"imageName"] forState:UIControlStateNormal];
[myButton setTitle:@"Rate us on app store" forState:UIControlStateNormal];
[myButton setTitleEdgeInsets:UIEdgeInsetsMake(2, 50, 2, 20)];//set ur title insects myButton
[myButton setImageEdgeInsets:UIEdgeInsetsMake(2, -200, 2, 2)];//make negative edge for left side
[myButton setBackgroundColor:[UIColor greenColor]];
[self.view myButton];