IOS上怎么画出1像素的线

IOS上如何画出1像素的线

#define SINGLE_LINE_WIDTH (1/[UIScreen mainScreen].scale)

#define SINGLE_LINE_ADJUST_OFFSET ((1/[UIScreen mainScreen].scale)/2)

- (void)viewDidLoad {

[super viewDidLoad];

// Do any additional setup after loading the view, typically from a nib.

CGFloat xPos = 100;

UIView *view = [[UIView alloc] initWithFrame:CGRectMake(xPos - SINGLE_LINE_ADJUST_OFFSET, 35, SINGLE_LINE_WIDTH, 330)];

view.backgroundColor = [UIColor blackColor];

[self.view addSubview:view];

}