CGRect frame = [self.view frame];
CGPoint topLeft = CGPointMake(CGRectGetMinX(frame), CGRectGetMinY(frame));
CGPoint topRight = CGPointMake(CGRectGetMaxX(frame), CGRectGetMinY(frame));
CGPoint bottomLeft = CGPointMake(CGRectGetMinX(frame), CGRectGetMaxY(frame));
CGPoint bottomRight = CGPointMake(CGRectGetMaxX(frame), CGRectGetMaxY(frame));
If you need those coordinates in a particular view, the first line should be something like
CGRect frame = [self.view convertRect:[self.view bounds] toView:someOtherView];