我如何从十六进制字符串格式创建一个UIColor,如#00FF00?
当前回答
张贴参考网站我刚刚找到。 它做了所有的脏工作,从HEX或RGB开始,在ObjC, Swift和Xamarin中打印出代码。
https://www.uicolor.xyz/#/hex-to-ui
其他回答
伊森·斯特里德回答的简单例子。一个接受十六进制字符串并返回UIColor的函数。 (你可以输入十六进制字符串格式:#ffffff或ffffff)
例子:
func hexStringToUIColor (hex:String) -> UIColor {
var cString: String = hex.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines).uppercased()
if (cString.hasPrefix("#")) {
if let range = cString.range(of: cString) {
cString = cString.substring(from: cString.index(range.lowerBound, offsetBy: 1))
}
}
if ((cString.characters.count) != 6) {
return UIColor.gray
}
var rgbValue: UInt32 = 0
Scanner(string: cString).scanHexInt32(&rgbValue)
return UIColor(
red: CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0,
green: CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0,
blue: CGFloat(rgbValue & 0x0000FF) / 255.0,
alpha: CGFloat(1.0)
)
}
用法:
var color1 = hexStringToUIColor("#d3d3d3")
我找到了一个很好的UIColor类别,UIColor+PXExtensions。
用法:UIColor *mycolor = [UIColor pxColorWithHexValue:@"#BADA55"];
而且,为了防止链接到我的要点失败,这里是实际的实现代码:
//
// UIColor+PXExtensions.m
//
#import "UIColor+UIColor_PXExtensions.h"
@implementation UIColor (UIColor_PXExtensions)
+ (UIColor*)pxColorWithHexValue:(NSString*)hexValue
{
//Default
UIColor *defaultResult = [UIColor blackColor];
//Strip prefixed # hash
if ([hexValue hasPrefix:@"#"] && [hexValue length] > 1) {
hexValue = [hexValue substringFromIndex:1];
}
//Determine if 3 or 6 digits
NSUInteger componentLength = 0;
if ([hexValue length] == 3)
{
componentLength = 1;
}
else if ([hexValue length] == 6)
{
componentLength = 2;
}
else
{
return defaultResult;
}
BOOL isValid = YES;
CGFloat components[3];
//Seperate the R,G,B values
for (NSUInteger i = 0; i < 3; i++) {
NSString *component = [hexValue substringWithRange:NSMakeRange(componentLength * i, componentLength)];
if (componentLength == 1) {
component = [component stringByAppendingString:component];
}
NSScanner *scanner = [NSScanner scannerWithString:component];
unsigned int value;
isValid &= [scanner scanHexInt:&value];
components[i] = (CGFloat)value / 256.0f;
}
if (!isValid) {
return defaultResult;
}
return [UIColor colorWithRed:components[0]
green:components[1]
blue:components[2]
alpha:1.0];
}
@end
有一个很好的帖子是关于如何解决OP的问题,从十六进制字符串中提取UIColor。下面给出的解决方案与其他解决方案不同,因为它支持字符串值,可能包括'0x'或'#'前缀的十六进制字符串表示…(请参阅使用)
这是主要的部分…
- (UIColor *)getUIColorObjectFromHexString:(NSString *)hexStr alpha:(CGFloat)alpha
{
// Convert hex string to an integer
unsigned int hexint = [self intFromHexString:hexStr];
// Create a color object, specifying alpha as well
UIColor *color =
[UIColor colorWithRed:((CGFloat) ((hexint & 0xFF0000) >> 16))/255
green:((CGFloat) ((hexint & 0xFF00) >> 8))/255
blue:((CGFloat) (hexint & 0xFF))/255
alpha:alpha];
return color;
}
助手方法……
- (unsigned int)intFromHexString:(NSString *)hexStr
{
unsigned int hexInt = 0;
// Create scanner
NSScanner *scanner = [NSScanner scannerWithString:hexStr];
// Tell scanner to skip the # character
[scanner setCharactersToBeSkipped:[NSCharacterSet characterSetWithCharactersInString:@"#"]];
// Scan hex value
[scanner scanHexInt:&hexInt];
return hexInt;
}
用法:
NSString *hexStr1 = @"123ABC";
NSString *hexStr2 = @"#123ABC";
NSString *hexStr3 = @"0x123ABC";
UIColor *color1 = [self getUIColorObjectFromHexString:hexStr1 alpha:.9];
NSLog(@"UIColor: %@", color1);
UIColor *color2 = [self getUIColorObjectFromHexString:hexStr2 alpha:.9];
NSLog(@"UIColor: %@", color2);
UIColor *color3 = [self getUIColorObjectFromHexString:hexStr3 alpha:.9];
NSLog(@"UIColor: %@", color3);
完整的参考文章
Swift 2 +
我已经将这个解决方案移植到Swift 2.2。注意,我已经将alpha参数更改为使用默认设置为1.0。我还根据Swift 2.2中的NSScanner类的要求将int类型更新为UInt32。
func colorWithHexString(hexString: String, alpha:CGFloat = 1.0) -> UIColor {
// Convert hex string to an integer
let hexint = Int(self.intFromHexString(hexString))
let red = CGFloat((hexint & 0xff0000) >> 16) / 255.0
let green = CGFloat((hexint & 0xff00) >> 8) / 255.0
let blue = CGFloat((hexint & 0xff) >> 0) / 255.0
// Create color object, specifying alpha as well
let color = UIColor(red: red, green: green, blue: blue, alpha: alpha)
return color
}
func intFromHexString(hexStr: String) -> UInt32 {
var hexInt: UInt32 = 0
// Create scanner
let scanner: NSScanner = NSScanner(string: hexStr)
// Tell scanner to skip the # character
scanner.charactersToBeSkipped = NSCharacterSet(charactersInString: "#")
// Scan hex value
scanner.scanHexInt(&hexInt)
return hexInt
}
斯威夫特 4+
采用与swift 4相同的变化逻辑,
func colorWithHexString(hexString: String, alpha:CGFloat = 1.0) -> UIColor {
// Convert hex string to an integer
let hexint = Int(self.intFromHexString(hexStr: hexString))
let red = CGFloat((hexint & 0xff0000) >> 16) / 255.0
let green = CGFloat((hexint & 0xff00) >> 8) / 255.0
let blue = CGFloat((hexint & 0xff) >> 0) / 255.0
// Create color object, specifying alpha as well
let color = UIColor(red: red, green: green, blue: blue, alpha: alpha)
return color
}
func intFromHexString(hexStr: String) -> UInt32 {
var hexInt: UInt32 = 0
// Create scanner
let scanner: Scanner = Scanner(string: hexStr)
// Tell scanner to skip the # character
scanner.charactersToBeSkipped = CharacterSet(charactersIn: "#")
// Scan hex value
scanner.scanHexInt32(&hexInt)
return hexInt
}
Swift 5 (iOS 13)+
下面显示了在SDK弃用scanHexInt32的情况下工作的更新。我将代码封装到Swift playground文件中。
//: A UIKit based Playground for presenting user interface
import UIKit
import PlaygroundSupport
class MyViewController : UIViewController {
override func loadView() {
let view = UIView()
view.backgroundColor = .white
let label = UILabel()
label.frame = CGRect(x: 150, y: 200, width: 200, height: 20)
label.text = "Hello World!"
label.textColor = colorWithHexString(hexString: "22F728")
view.addSubview(label)
self.view = view
}
func colorWithHexString(hexString: String, alpha:CGFloat = 1.0) -> UIColor {
// Convert hex string to an integer
let hexint = Int(self.intFromHexString(hexStr: hexString))
let red = CGFloat((hexint & 0xff0000) >> 16) / 255.0
let green = CGFloat((hexint & 0xff00) >> 8) / 255.0
let blue = CGFloat((hexint & 0xff) >> 0) / 255.0
// Create color object, specifying alpha as well
let color = UIColor(red: red, green: green, blue: blue, alpha: alpha)
return color
}
func intFromHexString(hexStr: String) -> UInt32 {
var hexInt: UInt32 = 0
// Create scanner
let scanner: Scanner = Scanner(string: hexStr)
// Tell scanner to skip the # character
scanner.charactersToBeSkipped = CharacterSet(charactersIn: "#")
// Scan hex value
hexInt = UInt32(bitPattern: scanner.scanInt32(representation: .hexadecimal) ?? 0)
return hexInt
}
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()
彩色十六进制参考 HTML颜色名称和代码 十六进制颜色编码
使用这个类别:
在文件UIColor+Hexadecimal.h中
#import <UIKit/UIKit.h>
@interface UIColor(Hexadecimal)
+ (UIColor *)colorWithHexString:(NSString *)hexString;
@end
在文件UIColor+Hexadecimal.m中
#import "UIColor+Hexadecimal.h"
@implementation UIColor(Hexadecimal)
+ (UIColor *)colorWithHexString:(NSString *)hexString {
unsigned rgbValue = 0;
NSScanner *scanner = [NSScanner scannerWithString:hexString];
[scanner setScanLocation:1]; // bypass '#' character
[scanner scanHexInt:&rgbValue];
return [UIColor colorWithRed:((rgbValue & 0xFF0000) >> 16)/255.0 green:((rgbValue & 0xFF00) >> 8)/255.0 blue:(rgbValue & 0xFF)/255.0 alpha:1.0];
}
@end
你想在课堂上使用它:
#import "UIColor+Hexadecimal.h"
and:
[UIColor colorWithHexString:@"#6e4b4b"];
extension UIColor {
convenience init(hexaString: String, alpha: CGFloat = 1) {
let chars = Array(hexaString.dropFirst())
self.init(red: .init(strtoul(String(chars[0...1]),nil,16))/255,
green: .init(strtoul(String(chars[2...3]),nil,16))/255,
blue: .init(strtoul(String(chars[4...5]),nil,16))/255,
alpha: alpha)}
}
用法:
let redColor = UIColor(hexaString: "#FF0000") // r 1,0 g 0,0 b 0,0 a 1,0
let transparentRed = UIColor(hexaString: "#FF0000", alpha: 0.5) // r 1,0 g 0,0 b 0,0 a 0,5
另一种选择是将六值转换为无符号整数,并从中提取相应的值:
extension UIColor {
convenience init(hexaString: String, alpha: CGFloat = 1) {
self.init(hexa: UInt(hexaString.dropFirst(), radix: 16) ?? 0, alpha: alpha)
}
convenience init(hexa: UInt, alpha: CGFloat = 1) {
self.init(red: .init((hexa & 0xff0000) >> 16) / 255,
green: .init((hexa & 0xff00 ) >> 8) / 255,
blue: .init( hexa & 0xff ) / 255,
alpha: alpha)
}
}
let purpleColor = UIColor(hexaString: "#FF00FF") // r 1,0 g 0,0 b 1,0 a 1,0
let transparentYellow = UIColor(hexaString: "#FFFF00", alpha: 0.5) // r 1,0 g 1,0 b 0,0 a 0,5
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