我如何从十六进制字符串格式创建一个UIColor,如#00FF00?
当前回答
斯威夫特的版本。作为函数或扩展使用。
Function func UIColorFromRGB(colorCode: String, alpha: Float = 1.0) -> UIColor{
var scanner = NSScanner(string:colorCode)
var color:UInt32 = 0;
scanner.scanHexInt(&color)
let mask = 0x000000FF
let r = CGFloat(Float(Int(color >> 16) & mask)/255.0)
let g = CGFloat(Float(Int(color >> 8) & mask)/255.0)
let b = CGFloat(Float(Int(color) & mask)/255.0)
return UIColor(red: r, green: g, blue: b, alpha: CGFloat(alpha))
}
Extension
extension UIColor {
convenience init(colorCode: String, alpha: Float = 1.0){
var scanner = NSScanner(string:colorCode)
var color:UInt32 = 0;
scanner.scanHexInt(&color)
let mask = 0x000000FF
let r = CGFloat(Float(Int(color >> 16) & mask)/255.0)
let g = CGFloat(Float(Int(color >> 8) & mask)/255.0)
let b = CGFloat(Float(Int(color) & mask)/255.0)
self.init(red: r, green: g, blue: b, alpha: CGFloat(alpha))
}
}
How to call
let hexColorFromFunction = UIColorFromRGB("F4C124", alpha: 1.0)
let hexColorFromExtension = UIColor(colorCode: "F4C124", alpha: 1.0)
You can also define your Hex Color
from interface builder.
其他回答
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
斯威夫特4
你可以像这样在扩展中创建一个非常方便的构造函数:
extension UIColor {
convenience init(hexString: String, alpha: CGFloat = 1.0) {
var hexInt: UInt32 = 0
let scanner = Scanner(string: hexString)
scanner.charactersToBeSkipped = CharacterSet(charactersIn: "#")
scanner.scanHexInt32(&hexInt)
let red = CGFloat((hexInt & 0xff0000) >> 16) / 255.0
let green = CGFloat((hexInt & 0xff00) >> 8) / 255.0
let blue = CGFloat((hexInt & 0xff) >> 0) / 255.0
let alpha = alpha
self.init(red: red, green: green, blue: blue, alpha: alpha)
}
}
以后再用
let color = UIColor(hexString: "#AABBCCDD")
另一个带有alpha的版本
#define UIColorFromRGBA(rgbValue) [UIColor colorWithRed:((float)((rgbValue & 0xFF000000) >> 24))/255.0 green:((float)((rgbValue & 0xFF0000) >> 16))/255.0 blue:((float)((rgbValue & 0xFF00) >> 8 ))/255.0 alpha:((float)((rgbValue & 0xFF))/255.0)]
据我所知,没有从十六进制字符串到UIColor(或CGColor)的内置转换。但是,您可以很容易地为此目的编写几个函数—例如,参见iphone开发访问uicolor组件
另一个实现允许字符串“FFF”或“FFFFFF”,并使用alpha:
+ (UIColor *) colorFromHexString:(NSString *)hexString alpha: (CGFloat)alpha{
NSString *cleanString = [hexString stringByReplacingOccurrencesOfString:@"#" withString:@""];
if([cleanString length] == 3) {
cleanString = [NSString stringWithFormat:@"%@%@%@%@%@%@",
[cleanString substringWithRange:NSMakeRange(0, 1)],[cleanString substringWithRange:NSMakeRange(0, 1)],
[cleanString substringWithRange:NSMakeRange(1, 1)],[cleanString substringWithRange:NSMakeRange(1, 1)],
[cleanString substringWithRange:NSMakeRange(2, 1)],[cleanString substringWithRange:NSMakeRange(2, 1)]];
}
if([cleanString length] == 6) {
cleanString = [cleanString stringByAppendingString:@"ff"];
}
unsigned int baseValue;
[[NSScanner scannerWithString:cleanString] scanHexInt:&baseValue];
float red = ((baseValue >> 24) & 0xFF)/255.0f;
float green = ((baseValue >> 16) & 0xFF)/255.0f;
float blue = ((baseValue >> 8) & 0xFF)/255.0f;
return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
}
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