使用 NSAttributedString 更改字符串颜色？

Question

我有一个用于调查的滑块，它根据滑块的值显示以下字符串：“非常差、差、好的、好、非常好”。

这是滑块的代码：

- (IBAction) sliderValueChanged:(UISlider *)sender {
    scanLabel.text = [NSString stringWithFormat:@" %.f", [sender value]];
    NSArray *texts=[NSArray arrayWithObjects:@"Very Bad", @"Bad", @"Okay", @"Good", @"Very Good", @"Very Good", nil];
    NSInteger sliderValue=[sender value]; //make the slider value in given range integer one.
    self.scanLabel.text=[texts objectAtIndex:sliderValue];
}

我希望“非常糟糕”为红色，“糟糕”为橙色，“还好”为黄色，“良好”和“非常好”为绿色。

我不明白如何使用NSAttributedString 来完成这项工作。

Answer 1

Swift 5.2 更新

var attributes = [NSAttributedString.Key: AnyObject]()

attributes[.foregroundColor] = UIColor.blue

let attributedString = NSAttributedString(string: "Very Bad",
attributes: attributes)

label.attributedText = attributedString

Answer 2

我喜欢让事情变得更简单，试试这个

-(NSArray *) reArrangeArrays:(NSArray *)iObjects {
    
    NSMutableArray *Words = [[NSMutableArray alloc] init];
    NSMutableArray *Colors = [[NSMutableArray alloc] init];
    
    CFIndex OneThree = 0;
    CFIndex TwoFour = 1;
    for (CFIndex iCounter = 0; iCounter < iObjects.count; iCounter ++) {
        
        [Words addObject:[iObjects objectAtIndex:OneThree]];
        [Colors addObject:[iObjects objectAtIndex:TwoFour]];
        
        OneThree = OneThree + 2;
        TwoFour = TwoFour + 2;
        
        if (OneThree > iObjects.count || TwoFour > iObjects.count)
            break;
    }
    
    return @[[NSArray arrayWithArray:Words],[NSArray arrayWithArray:Colors]];
}

+(NSMutableAttributedString *) OriginalText:(NSString *)OriginalText WordsAndColors:(NSArray *)WordsAndColors TheRestOfTheTextColor:(UIColor *)TheRestColor {
    
    NSArray *Text = [[self.alloc reArrangeArrays:WordsAndColors] objectAtIndex:0];
    NSArray *Color = [[self.alloc reArrangeArrays:WordsAndColors] objectAtIndex:1];

    NSMutableAttributedString *MutableAttString = [[NSMutableAttributedString alloc] initWithString:OriginalText attributes:@{NSForegroundColorAttributeName : TheRestColor}];

    NSString *text = OriginalText;

    if (OriginalText != nil) {

    for (NSUInteger Counter = 0; Counter < Color.count; Counter ++) {

    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:[NSString stringWithFormat:@"(%@)",[Text objectAtIndex:Counter]] options:kNilOptions error:nil];

    NSRange range = NSMakeRange(0 ,text.length);

    [regex enumerateMatchesInString:text options:kNilOptions range:range usingBlock:^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop) {

        NSRange subStringRange = [result rangeAtIndex:0];

        [MutableAttString addAttribute:NSForegroundColorAttributeName value:[Color objectAtIndex:Counter] range:subStringRange];

    }];


    }
}
    return MutableAttString;
}

这就是使用方法

 NSString *Text = @"Made by @CrazyMind90";
        
 NSMutableAttributedString *AttriString = [ViewController OriginalText:Text
            WordsAndColors:@[
                
            @"Made",UIColor.redColor,
            @"by",UIColor.yellowColor,
            @"@CrazyMind90",UIColor.blueColor,
            
            ]
            
           TheRestOfTheTextColor:UIColor.whiteColor];
        
    
           //Not TextView.text BUT TextView.attributedText
           TextView.attributedText = AttriString;

The result

..

Answer 3

对于 Swift 5：

var attributes = [NSAttributedString.Key: AnyObject]()
attributes[.foregroundColor] = UIColor.red

let attributedString = NSAttributedString(string: "Very Bad", attributes: attributes)

label.attributedText = attributedString

对于 Swift 4：

var attributes = [NSAttributedStringKey: AnyObject]()
attributes[.foregroundColor] = UIColor.red

let attributedString = NSAttributedString(string: "Very Bad", attributes: attributes)

label.attributedText = attributedString

对于 Swift 3：

var attributes = [String: AnyObject]()
attributes[NSForegroundColorAttributeName] = UIColor.red

let attributedString = NSAttributedString(string: "Very Bad", attributes: attributes)

label.attributedText = attributedString

Answer 4

Swift 的一个衬里：

NSAttributedString(string: "Red Text", attributes: [.foregroundColor: UIColor.red])

Answer 5

您可以创建NSAttributedString

NSDictionary *attributes = @{ NSForegroundColorAttributeName : [UIColor redColor] };
NSAttributedString *attrStr = [[NSAttributedString alloc] initWithString:@"My Color String" attributes:attrs];

OR NSMutableAttributedString 将自定义属性与 Ranges 一起应用。

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:[NSString stringWithFormat:@"%@%@", methodPrefix, method] attributes: @{ NSFontAttributeName : FONT_MYRIADPRO(48) }];
[attributedString addAttribute:NSFontAttributeName value:FONT_MYRIADPRO_SEMIBOLD(48) range:NSMakeRange(methodPrefix.length, method.length)];

可用属性：NSAttributedStringKey

---

更新：

斯威夫特 5.1

let message: String = greeting + someMessage
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = 2.0
    
// Note: UIFont(appFontFamily:ofSize:) is extended init.
let regularAttributes: [NSAttributedString.Key : Any] = [.font : UIFont(appFontFamily: .regular, ofSize: 15)!, .paragraphStyle : paragraphStyle]
let boldAttributes = [NSAttributedString.Key.font : UIFont(appFontFamily: .semiBold, ofSize: 15)!]

let mutableString = NSMutableAttributedString(string: message, attributes: regularAttributes)
mutableString.addAttributes(boldAttributes, range: NSMakeRange(0, greeting.count))

Answer 6

在 Swift 4 中：

// Custom color
let greenColor = UIColor(red: 10/255, green: 190/255, blue: 50/255, alpha: 1)
// create the attributed colour
let attributedStringColor = [NSAttributedStringKey.foregroundColor : greenColor];
// create the attributed string
let attributedString = NSAttributedString(string: "Hello World!", attributes: attributedStringColor)
// Set the label
label.attributedText = attributedString

在 Swift 3 中：

// Custom color
let greenColor = UIColor(red: 10/255, green: 190/255, blue: 50/255, alpha: 1)
// create the attributed color
let attributedStringColor : NSDictionary = [NSForegroundColorAttributeName : greenColor];
// create the attributed string
let attributedString = NSAttributedString(string: "Hello World!", attributes: attributedStringColor as? [String : AnyObject])
// Set the label
label.attributedText = attributedString 

享受吧。

Answer 7

在 Swift 4 中，NSAttributedStringKey 有一个名为 foregroundColor 的静态属性。 foregroundColor 有以下声明：

static let foregroundColor: NSAttributedStringKey

这个属性的值是一个UIColor 对象。使用此属性可在渲染期间指定文本的颜色。如果不指定此属性，则文本呈现为黑色。

以下 Playground 代码显示了如何使用 foregroundColor 设置 NSAttributedString 实例的文本颜色：

import UIKit

let string = "Some text"
let attributes = [NSAttributedStringKey.foregroundColor : UIColor.red]
let attributedString = NSAttributedString(string: string, attributes: attributes)

---

下面的代码显示了一个可能的UIViewController 实现，它依赖于NSAttributedString 以便从UISlider 更新UILabel 的文本和文本颜色：

import UIKit

enum Status: Int {
    case veryBad = 0, bad, okay, good, veryGood

    var display: (text: String, color: UIColor) {
        switch self {
        case .veryBad:  return ("Very bad", .red)
        case .bad:      return ("Bad", .orange)
        case .okay:     return ("Okay", .yellow)
        case .good:     return ("Good", .green)
        case .veryGood: return ("Very good", .blue)
        }
    }

    static let minimumValue = Status.veryBad.rawValue
    static let maximumValue = Status.veryGood.rawValue
}

final class ViewController: UIViewController {

    @IBOutlet weak var label: UILabel!
    @IBOutlet weak var slider: UISlider!
    var currentStatus: Status = Status.veryBad {
        didSet {
            // currentStatus is our model. Observe its changes to update our display
            updateDisplay()
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        // Prepare slider
        slider.minimumValue = Float(Status.minimumValue)
        slider.maximumValue = Float(Status.maximumValue)

        // Set display
        updateDisplay()
    }

    func updateDisplay() {
        let attributes = [NSAttributedStringKey.foregroundColor : currentStatus.display.color]
        let attributedString = NSAttributedString(string: currentStatus.display.text, attributes: attributes)
        label.attributedText = attributedString
        slider.value = Float(currentStatus.rawValue)
    }

    @IBAction func updateCurrentStatus(_ sender: UISlider) {
        let value = Int(sender.value.rounded())
        guard let status = Status(rawValue: value) else { fatalError("Could not get Status object from value") }
        currentStatus = status
    }

}

但是请注意，对于这样的示例，您实际上并不需要使用NSAttributedString，而可以简单地依赖UILabel 的text 和textColor 属性。因此，您可以将 updateDisplay() 实现替换为以下代码：

func updateDisplay() {
    label.text = currentStatus.display.text
    label.textColor = currentStatus.display.color
    slider.value = Float(currentStatus.rawValue)
}

Answer 8

没有必要使用NSAttributedString。您所需要的只是一个带有正确textColor 的简单标签。此外，这个简单的解决方案适用于所有版本的 iOS，而不仅仅是 iOS 6。

但如果你不必要地希望使用NSAttributedString，你可以这样做：

UIColor *color = [UIColor redColor]; // select needed color
NSString *string = ... // the string to colorize
NSDictionary *attrs = @{ NSForegroundColorAttributeName : color };
NSAttributedString *attrStr = [[NSAttributedString alloc] initWithString:string attributes:attrs];
self.scanLabel.attributedText = attrStr;

Answer 9

使用类似的东西（未检查编译器）

NSMutableAttributedString *string = [[NSMutableAttributedString alloc]initWithString:self.text.text];
NSRange range=[self.myLabel.text rangeOfString:texts[sliderValue]]; //myLabel is the outlet from where you will get the text, it can be same or different

NSArray *colors=@[[UIColor redColor],
                  [UIColor redColor],
                  [UIColor yellowColor],
                  [UIColor greenColor]
                 ];

[string addAttribute:NSForegroundColorAttributeName 
               value:colors[sliderValue] 
               range:range];           

[self.scanLabel setAttributedText:texts[sliderValue]];