ios - Why does calculate text bounds is different between UILabel and CoreText?

Question

It has the same height between iOS13 Or iOS 14 with the same words in the label . But It's different from when I use the CoreText .For example:

click the UIlabel and obtain the last line bounds with CoreText is different

    NSMutableAttributedString *attri = [[NSMutableAttributedString alloc]initWithString:@"107年前（743年），世界上突然出现了人类的天敌“巨人”。面临着生存危机而残存下来的。107年前（743年），世界上突然出现了人类的天敌“巨人”。面临着生存危机而残存下来的。107年前（743年），世界上突然出现了人类的天敌“巨人”。面临着生存危机而残存下来的。107年前（743年），世界上突然出现了人类的天敌“巨人”。面临着生存危机而残存下来的。];
    [attri addAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:16]} range:NSMakeRange(0, attri.length)];
        NSMutableParagraphStyle *paraStyle = [NSMutableParagraphStyle new];
        paraStyle.lineSpacing = 4;
        
        [attri addAttribute:NSParagraphStyleAttributeName value:paraStyle range:NSMakeRange(0, attri.length)];

In iOS 13 or iOS 14 The UIlabel Bounds is CGRect(0 0; 232 250.5)

But the result of Coretext obtain the LastLine Height In iOS13 is (CGRect) lineBounds = (origin = (x = 0, y = 212.24000000000001), size = (width = 114.23999999999998, height = 16));

the result of Coretext LastLine Height In iOS14 is (CGRect) lineBounds = (origin = (x = 0, y = 231.24000000000001), size = (width = 114.23999999999998, height = 16));

why it's different betweeen iOS 13 and iOS14 about the point.y

question from:https://stackoverflow.com/questions/66057278/why-does-calculate-text-bounds-is-different-between-uilabel-and-coretext

Answer 1

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