ios - 在 iOS 中将字符串转换为十六进制？

Question

我主要是让用户在 UITextField 中输入一个十六进制值，并将其写入一个字符串中，以将其用于颜色选择(教育目的)。如何将字符串转换为十六进制？

Answer 1

我不确定这是否是您在您的场景中想要的...看看这是否有用..

通过传递十六进制字符串调用第一个方法，作为返回，您将获得UIColor。

- (UIColor *) colorWithHexString:(NSString *)hexString {
    NSString *colorString = [[hexString stringByReplacingOccurrencesOfString: @"#" withString: @""] uppercaseString];
    CGFloat alpha, red, blue, green;
    alpha = 1.0f;
    red   = [self colorComponentFrom: colorString start: 0 length: 2];
    green = [self colorComponentFrom: colorString start: 2 length: 2];
    blue  = [self colorComponentFrom: colorString start: 4 length: 2];
    return [UIColor colorWithRed: red green: green blue: blue alpha: alpha];
}

- (CGFloat) colorComponentFrom:(NSString *)string start:(NSUInteger)start length:(NSUInteger)length {
    NSString *substring = [string substringWithRange: NSMakeRange(start, length)];
    NSString *fullHex = length == 2 ? substring : [NSString stringWithFormat: @"%@%@", substring, substring];
    unsigned hexComponent;
    [[NSScanner scannerWithString: fullHex] scanHexInt: &hexComponent];
    return hexComponent / 255.0;
}