CoreTextを使って描画した文字をリンカブルにする

gistfile1.m

#import "YMNCoreTextView.h"
#import <CoreText/CoreText.h>
#import <QuartzCore/QuartzCore.h>

@interface YMNCoreTextView()

@property (nonatomic, strong) NSMutableAttributedString *attributedString;
@property (nonatomic, assign) CTFrameRef drawingFrame;
@property (nonatomic, assign) NSRange linkableWordRange;

@end

@implementation YMNCoreTextView

- (id)initWithText:(NSString*)text item:(NSArray*)items {
    self = [super init];
    if (self) {
        [self setText];
    }
    return self;
}

- (void)setText {
    NSString *text = @"Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
    
    CTFontRef fontRef = CTFontCreateWithName((CFStringRef)@"HiraKakuProN-W3", 12.0f, nil);
    NSDictionary *attrDictionary = @{(NSString *)kCTFontAttributeName:(__bridge id)fontRef};
    CFRelease(fontRef);
    self.attributedString = [[NSMutableAttributedString alloc] initWithString:text attributes:attrDictionary];
    
    // リンカブルっぽく青文字で下線付きの属性を作る
    CTFontRef linkableFontRef = CTFontCreateWithName((CFStringRef)@"HiraKakuProN-W6", 12.0f, nil);
    NSDictionary *linkableAttrDictionary = @{(NSString *)kCTFontAttributeName:(__bridge id)linkableFontRef,
                                             (NSString *)kCTForegroundColorAttributeName:(id)[UIColor blueColor].CGColor,
                                             (NSString *)kCTUnderlineStyleAttributeName:@(kCTUnderlineStyleSingle)};
    
    // リンカブルにしたい文字のrangeと属性を指定して attributedString に追加
    self.linkableWordRange = [text rangeOfString:@"consectetur"];
    [self.attributedString addAttributes:linkableAttrDictionary range:self.linkableWordRange];
    CFRelease(linkableFontRef);
}

- (void)drawRect:(CGRect)rect {
    [super drawRect:rect];
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    // iPhone の座標系と Core Graphics の座標系は、左下が原点なためそのまま描画をすると反転してしまう
    // CGContextSetTextMatrix で反転させ CGContextTranslateCTM で並行移動
    CGContextSetTextMatrix(context, CGAffineTransformIdentity);
    CGContextTranslateCTM(context, 0.f, rect.size.height);
    CGContextScaleCTM(context, 1.f, -1.f);
    
    // 描画範囲を設定して描画
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddRect(path, NULL, CGRectMake(0.f, 0.f, rect.size.width, rect.size.height));
    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)self.attributedString);
    self.drawingFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0.f, self.attributedString.length), path, nil);
    CTFrameDraw(self.drawingFrame, context);
    CFRelease(framesetter);
    CFRelease(path);
}

- (NSRange)rangeOfPoint:(CGPoint)point {
    // CTFrameからCTLineの配列を取得
    CFArrayRef lines = CTFrameGetLines(self.drawingFrame);
    
    // CTFrameからCTLineの原点座標を取得
    CGPoint *origins = malloc(sizeof(CGPoint) * CFArrayGetCount(lines));
    CTFrameGetLineOrigins(self.drawingFrame, CFRangeMake(0, 0), origins);
    
    NSRange range;
    for (int i = 0; i < CFArrayGetCount(lines); i++) {
        // i番目のCTLineを取得
        CTLineRef line = CFArrayGetValueAtIndex(lines, i);
        
        // i番目のCTLineの原点座標
        CGPoint origin = *(origins + i);
        
        // 行のframeを計算
        CGFloat ascent = 0;
        CGFloat descent = 0;
        CGFloat lineWidth = CTLineGetTypographicBounds(line, &ascent, &descent, nil);
        CGRect lineFrame = CGRectMake(origin.x, origin.y - descent, lineWidth, ascent + descent);
        
        // タッチされた座標がCTLineのframe内にあるかどうか判定
        if (CGRectContainsPoint(lineFrame, point)) {
            // タッチされた文字列のインデックスを取得
            CFIndex index = CTLineGetStringIndexForPosition(line, point);
            if (index == kCFNotFound) {
                continue;
            }
            
            // タッチされた文字列の属性を取得
            [self.attributedString attributesAtIndex:index effectiveRange:&range];
        }
    }
    
    if (origins) {
        free(origins), origins = nil;
    }
    
    return range;
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    CGPoint point = [(UITouch*)[touches anyObject] locationInView:self];
    point.y = CGRectGetHeight(self.bounds) - point.y;
    
    // タッチされた文字列のrangeを取得
    NSRange touchedRange = [self rangeOfPoint:point];
    
    // タッチされた文字列のrangeがリンク文字のrangeに含まれているかどうか判定
    if (NSIntersectionRange(touchedRange, self.linkableWordRange).length > 0) {
        // リンク文字をタップされた時の処理を書く
        // ここではとりあえずログでも出しておく
        NSLog(@"タップされたよ location:%lu length:%lu",self.linkableWordRange.location, self.linkableWordRange.length);
    }
    
    [super touchesEnded:touches withEvent:event];
}

@end