iOS/Objective-C UILabel 文本字距调整

Question

我正在寻找如何增加 UILabel 中的字符间距以使我的 UI 应用程序设计实现更具吸引力。我发现下面的，它写在 Swift.

但我需要的是 Objective-C 解决方案。所以我尝试转换以下代码片段：

import UIKit
@IBDesignable
class KerningLabel: UILabel {
    @IBInspectable var kerning:CGFloat = 0.0{
        didSet{
            if ((self.attributedText?.length) != nil)
            {
                let attribString = NSMutableAttributedString(attributedString: self.attributedText!)
                attribString.addAttributes([NSKernAttributeName:kerning], range:NSMakeRange(0, self.attributedText!.length))
                self.attributedText = attribString
            }
        }
    }
}

关注Objective-C：
KerningLabel.h:

#import <UIKit/UIKit.h>
IB_DESIGNABLE
@interface KerningLabel : UILabel
@property (nonatomic) IBInspectable CGFloat kerning;
@end

KerningLabel.m:

#import "KerningLabel.h"

@implementation KerningLabel
@synthesize kerning;
- (void) setAttributedText:(NSAttributedString *)attributedText {
    if ([self.attributedText length] > 0) {
        NSMutableAttributedString *muAttrString = [[NSMutableAttributedString alloc] initWithAttributedString:self.attributedText];
        [muAttrString addAttribute:NSKernAttributeName value:@(self.kerning) range:NSMakeRange(0, [self.attributedText length])];
        self.attributedText = muAttrString;
    }
}
@end

并且它在XCode IB中给出了以下属性来调整字距，

但当应用程序运行时，它似乎并没有在 UI 上生效，而且在 Interface Builder 中文本消失了。

请有人帮助我并指出我做错了什么。

感谢进阶！

Answer 1

您想在每次更新字距调整时更新您的 attributedText。所以，你的 .h 应该是这样的：

IB_DESIGNABLE
@interface KerningLabel : UILabel

@property (nonatomic) IBInspectable CGFloat kerning;

@end

和你的 .m :

@implementation KerningLabel

- (void)setKerning:(CGFloat)kerning
{
    _kerning = kerning;

    if(self.attributedText)
    {
        NSMutableAttributedString *attribString = [[NSMutableAttributedString alloc]initWithAttributedString:self.attributedText];
        [attribString addAttribute:NSKernAttributeName value:@(kerning) range:NSMakeRange(0, self.attributedText.length)];
        self.attributedText = attribString;
     }
}

@end

iOS/Objective-C UILabel 文本字距调整

iOS/Objective-C UILabel text kerning

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objective-c

interface-builder

uilabel

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