细节
Swift 5.2, Xcode 11.4 (11E146)
解决方案
protocol AttributedStringComponent {
var text: String { get }
func getAttributes() -> [NSAttributedString.Key: Any]?
}
// MARK: String extensions
extension String: AttributedStringComponent {
var text: String { self }
func getAttributes() -> [NSAttributedString.Key: Any]? { return nil }
}
extension String {
func toAttributed(with attributes: [NSAttributedString.Key: Any]?) -> NSAttributedString {
.init(string: self, attributes: attributes)
}
}
// MARK: NSAttributedString extensions
extension NSAttributedString: AttributedStringComponent {
var text: String { string }
func getAttributes() -> [Key: Any]? {
if string.isEmpty { return nil }
var range = NSRange(location: 0, length: string.count)
return attributes(at: 0, effectiveRange: &range)
}
}
extension NSAttributedString {
convenience init?(from attributedStringComponents: [AttributedStringComponent],
defaultAttributes: [NSAttributedString.Key: Any],
joinedSeparator: String = " ") {
switch attributedStringComponents.count {
case 0: return nil
default:
var joinedString = ""
typealias SttributedStringComponentDescriptor = ([NSAttributedString.Key: Any], NSRange)
let sttributedStringComponents = attributedStringComponents.enumerated().flatMap { (index, component) -> [SttributedStringComponentDescriptor] in
var components = [SttributedStringComponentDescriptor]()
if index != 0 {
components.append((defaultAttributes,
NSRange(location: joinedString.count, length: joinedSeparator.count)))
joinedString += joinedSeparator
}
components.append((component.getAttributes() ?? defaultAttributes,
NSRange(location: joinedString.count, length: component.text.count)))
joinedString += component.text
return components
}
let attributedString = NSMutableAttributedString(string: joinedString)
sttributedStringComponents.forEach { attributedString.addAttributes($0, range: $1) }
self.init(attributedString: attributedString)
}
}
}
使用
let defaultAttributes = [
.font: UIFont.systemFont(ofSize: 16, weight: .regular),
.foregroundColor: UIColor.blue
] as [NSAttributedString.Key : Any]
let marketingAttributes = [
.font: UIFont.systemFont(ofSize: 20.0, weight: .bold),
.foregroundColor: UIColor.black
] as [NSAttributedString.Key : Any]
let attributedStringComponents = [
"pay for",
NSAttributedString(string: "one",
attributes: marketingAttributes),
"and get",
"three!\n".toAttributed(with: marketingAttributes),
"Only today!".toAttributed(with: [
.font: UIFont.systemFont(ofSize: 16.0, weight: .bold),
.foregroundColor: UIColor.red
])
] as [AttributedStringComponent]
let attributedText = NSAttributedString(from: attributedStringComponents, defaultAttributes: defaultAttributes)
完整的示例
不要忘记在这里粘贴解决方案代码
import UIKit
class ViewController: UIViewController {
private weak var label: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
let label = UILabel(frame: .init(x: 40, y: 40, width: 300, height: 80))
label.numberOfLines = 2
view.addSubview(label)
self.label = label
let defaultAttributes = [
.font: UIFont.systemFont(ofSize: 16, weight: .regular),
.foregroundColor: UIColor.blue
] as [NSAttributedString.Key : Any]
let marketingAttributes = [
.font: UIFont.systemFont(ofSize: 20.0, weight: .bold),
.foregroundColor: UIColor.black
] as [NSAttributedString.Key : Any]
let attributedStringComponents = [
"pay for",
NSAttributedString(string: "one",
attributes: marketingAttributes),
"and get",
"three!\n".toAttributed(with: marketingAttributes),
"Only today!".toAttributed(with: [
.font: UIFont.systemFont(ofSize: 16.0, weight: .bold),
.foregroundColor: UIColor.red
])
] as [AttributedStringComponent]
label.attributedText = NSAttributedString(from: attributedStringComponents, defaultAttributes: defaultAttributes)
label.textAlignment = .center
}
}
结果
