Hairline of iOS

hairline.m

/**
 *  Width of hairline (1px on real device screen)
 *  The dppx of screens can be found here http://dpi.lv/
 *
 *  @return CGFloat number to be set for "1px"
 */
+ (CGFloat)hairLineWidth {
    if ([UIScreen mainScreen].bounds.size.width == 414.f) { // Plus
        return 1.f / 2.46f; // 2.46 is the dppx of plus screens
    } else {
        return 1.f / [UIScreen mainScreen].scale; // for other screens, dppx is just as same as scale
    }
}

hairline.swift

// Swift 4 version

/// Width of hairline (1px on real device screen), the dppx of screens can be found here http://dpi.lv/
var hairLineWidth: CGFloat {
    if UIScreen.main.bounds.width == 414 { // plus
        return 1.0 / 2.46 // 2.46 is the dppx of plus screens
    } else {
        return 1.0 / UIScreen.main.scale // for other screens, dppx is just as same as scale
    }
}

看不下去了 必须star