TestChineseFallback.m

#import <Foundation/Foundation.h>
#import <CoreText/CoreText.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        CTFontRef font = CTFontCreateUIFontForLanguage(kCTFontUIFontSystem, 12, NULL);
        {
            CTFontRef fallback = CTFontCreateForStringWithLanguage(font, CFSTR("\u4E2D"), CFRangeMake(0, 1), CFSTR("zh-Hans"));
            CFCharacterSetRef covered = CTFontCopyCharacterSet(fallback);
            bool isMember = CFCharacterSetIsCharacterMember(covered, 0x61);
            NSLog(@"%d", isMember);
        }

        {
            NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:@"\u4E2D" attributes:@{ (id)kCTFontAttributeName: CFBridgingRelease(font) }];
            CTLineRef line = CTLineCreateWithAttributedString((CFAttributedStringRef)attrString);
            CFArrayRef runs = CTLineGetGlyphRuns(line);
            CTRunRef run = (CTRunRef)CFArrayGetValueAtIndex(runs, 0);
            CFDictionaryRef attributes = CTRunGetAttributes(run);
            CTFontRef fallback = CFDictionaryGetValue(attributes, kCTFontAttributeName);
            CFCharacterSetRef covered = CTFontCopyCharacterSet(fallback);
            bool isMember = CFCharacterSetIsCharacterMember(covered, 0x61);
            NSLog(@"%d", isMember);
        }
    }
    return 0;
}