3 
- (void)setStrokeLabel:(BOOL)strokeLabel
{
    _strokeLabel = strokeLabel;

    if (_strokeLabel) {
        _timer = [NSTimer scheduledTimerWithTimeInterval:0.4 target:self selector:@selector(setStrokeThrough) userInfo:nil repeats:NO];
    } else {
        [self cancelStrokeThrough];
    }
}

- (void)setStrokeThrough
{
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithAttributedString:self.attributedText];

    for (NSUInteger i = 1; i <= [attributedString length]; i++) {
        [attributedString addAttribute:NSStrikethroughStyleAttributeName
                                 value:[NSNumber numberWithInt:1]
                                 range:NSMakeRange(0, i)];
        self.attributedText = attributedString;
    }
}

- (void)cancelStrokeThrough
{
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithAttributedString:self.attributedText];
    [attributedString removeAttribute:NSStrikethroughStyleAttributeName
                                range:NSMakeRange(0, [attributedString length])];
    self.attributedText = attributedString;

}

我想制作动画strike-through，比如 todo done 动画。当我为它设置定时器时，定时器只处理如何逐个字母地显示笔触？

4

1 回答 1

2

这是完成这项工作的两个函数。

    BOOL setStrokethrough(UILabel *label, NSRange range)
    {
        if (range.location >= [label.attributedText length])
            return FALSE;

        if (range.location + range.length > [label.attributedText length])
            range.length = [label.attributedText length] - range.location;

        NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithAttributedString:label.attributedText];

        [attributedString addAttribute:NSStrikethroughStyleAttributeName
                                 value:@(NSUnderlineStyleSingle)
                                 range:range];

        label.attributedText = attributedString;
        return TRUE;
    }

    -(void)animateSetStrokethroughDuration:(float)duration
    {
        __block float const stepDuration = 0.1;
        float steps = duration / stepDuration;
        __block NSRange range = NSMakeRange(0, ceil((float)[self.label.attributedText length] / steps));

        void (^__block fn)();
        void (^__block __weak weakfn)();

        weakfn = fn = ^(){
            if (!setStrokethrough(self.label, range))
                return;
            range = NSMakeRange(range.location + range.length, range.length);
            [self performBlock:weakfn afterDelay:stepDuration];
        };
        fn();
    }

笔记

  1. 为了限制动画时间，我按角色块制作动画，而不是按角色制作动画。字符串越长，字符块就越长。
  2. __block __weak business 在这里解释
  3. self performBlock 是Mike Ash对 NSObject 的扩展，也在这里
  4. 该代码假设您定义了 self.label 成员
于 2013-05-01T07:10:34.460 回答