解決YYLabel在IOS11文字高度計算與純中文垂直置中結果不如預期的問題

YYTextLine+Swizzle.h

//
//  YYTextLine+Swizzle.h
//  Created by Daniel Hsieh on 2018/8/1.
//  REF: https://github.com/ibireme/YYText/issues/748#issuecomment-364879873
//  ISSUES: https://github.com/ibireme/YYText/issues/748
//

#import "YYTextLine.h"

@interface YYTextLine (Swizzle)

@end

YYTextLine+Swizzle.m

//
//  YYTextLine+Swizzle.m
//  Created by Daniel Hsieh on 2018/8/1.
//  REF: https://github.com/ibireme/YYText/issues/748#issuecomment-364879873
//  ISSUES: https://github.com/ibireme/YYText/issues/748
//

#import <objc/runtime.h>

#import "YYTextLine+Swizzle.h"


@implementation YYTextLine (Swizzle)

+ (void)load {
    Method original, swizzled;
    original = class_getInstanceMethod(objc_getClass("YYTextLine"), NSSelectorFromString(@"setCTLine:"));
    swizzled = class_getInstanceMethod(self, @selector(swizzled_setCTLine:));
    method_exchangeImplementations(original, swizzled);
}

- (void)swizzled_setCTLine:(_Nonnull CTLineRef)CTLine {
    // _CTLine
    CTLineRef *_CTLinePtr = ({
        Ivar ivar = class_getInstanceVariable([self class], "_CTLine");
        ptrdiff_t offset = ivar_getOffset(ivar);
        unsigned char* bytes = (unsigned char *)(__bridge void*)self;
        CTLineRef *ptr = (CTLineRef *)(bytes+offset);
        ptr;
    });
    
    // _ascent
    CGFloat *_ascentPtr = ({
        Ivar ivar = class_getInstanceVariable([self class], "_ascent");
        ptrdiff_t offset = ivar_getOffset(ivar);
        unsigned char* bytes = (unsigned char *)(__bridge void*)self;
        CGFloat *ptr = (CGFloat *)(bytes+offset);
        ptr;
    });
    
    // _descent
    CGFloat *_descentPtr = ({
        Ivar ivar = class_getInstanceVariable([self class], "_descent");
        ptrdiff_t offset = ivar_getOffset(ivar);
        unsigned char* bytes = (unsigned char *)(__bridge void*)self;
        CGFloat *ptr = (CGFloat *)(bytes+offset);
        ptr;
    });
    
    // _leading
    CGFloat *_leadingPtr = ({
        Ivar ivar = class_getInstanceVariable([self class], "_leading");
        ptrdiff_t offset = ivar_getOffset(ivar);
        unsigned char* bytes = (unsigned char *)(__bridge void*)self;
        CGFloat *ptr = (CGFloat *)(bytes+offset);
        ptr;
    });
    
    // _lineWidth
    CGFloat *_lineWidthPtr = ({
        Ivar ivar = class_getInstanceVariable([self class], "_lineWidth");
        ptrdiff_t offset = ivar_getOffset(ivar);
        unsigned char* bytes = (unsigned char *)(__bridge void*)self;
        CGFloat *ptr = (CGFloat *)(bytes+offset);
        ptr;
    });
    
    // _range
    NSRange *_rangePtr = ({
        Ivar ivar = class_getInstanceVariable([self class], "_range");
        ptrdiff_t offset = ivar_getOffset(ivar);
        unsigned char* bytes = (unsigned char *)(__bridge void*)self;
        NSRange *ptr = (NSRange *)(bytes+offset);
        ptr;
    });
    
    // _firstGlyphPos
    CGFloat *_firstGlyphPosPtr = ({
        Ivar ivar = class_getInstanceVariable([self class], "_firstGlyphPos");
        ptrdiff_t offset = ivar_getOffset(ivar);
        unsigned char* bytes = (unsigned char *)(__bridge void*)self;
        CGFloat *ptr = (CGFloat *)(bytes+offset);
        ptr;
    });
    
    // _trailingWhitespaceWidth
    CGFloat *_trailingWhitespaceWidthPtr = ({
        Ivar ivar = class_getInstanceVariable([self class], "_trailingWhitespaceWidth");
        ptrdiff_t offset = ivar_getOffset(ivar);
        unsigned char* bytes = (unsigned char *)(__bridge void*)self;
        CGFloat *ptr = (CGFloat *)(bytes+offset);
        ptr;
    });
    
    if (*_CTLinePtr != CTLine) {
        if (CTLine) CFRetain(CTLine);
        if (*_CTLinePtr) CFRelease(*_CTLinePtr);
        *_CTLinePtr = CTLine;
        if (*_CTLinePtr) {
            *_lineWidthPtr = CTLineGetTypographicBounds(*_CTLinePtr, _ascentPtr, _descentPtr, _leadingPtr);
            if (@available(iOS 11.0, *)) {
                CGRect tempRect = CTLineGetBoundsWithOptions(*_CTLinePtr, 0);
                if (*_descentPtr > tempRect.size.height) {
                    *_descentPtr = tempRect.size.height - *_ascentPtr;
                }
            }
            
            CFRange range = CTLineGetStringRange(*_CTLinePtr);
            *_rangePtr = NSMakeRange(range.location, range.length);
            if (CTLineGetGlyphCount(*_CTLinePtr) > 0) {
                CFArrayRef runs = CTLineGetGlyphRuns(*_CTLinePtr);
                CTRunRef run = CFArrayGetValueAtIndex(runs, 0);
                CGPoint pos;
                CTRunGetPositions(run, CFRangeMake(0, 1), &pos);
                *_firstGlyphPosPtr = pos.x;
            } else {
                *_firstGlyphPosPtr = 0;
            }
            *_trailingWhitespaceWidthPtr = CTLineGetTrailingWhitespaceWidth(*_CTLinePtr);
        } else {
            *_lineWidthPtr = *_ascentPtr = *_descentPtr = *_leadingPtr = *_firstGlyphPosPtr = *_trailingWhitespaceWidthPtr = 0;
            *_rangePtr = NSMakeRange(0, 0);
        }
        
        // [self reloadBounds];
        SEL sel = NSSelectorFromString(@"reloadBounds");
        IMP imp = class_getMethodImplementation(objc_getClass("YYTextLine"), sel);
        ((void(*)(id, SEL))imp)(self, sel);
        
    }
}

@end