CoreTextを使って特定の文字をリンクっぽい見た目にする

gistfile1.m

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

@interface YMNCoreTextView()

@property (nonatomic, strong) NSMutableAttributedString *attributedString;

@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.attributedString addAttributes:linkableAttrDictionary range:[text rangeOfString:@"consectetur"]];
    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);
    CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0.f, self.attributedString.length), path, nil);
    CTFrameDraw(frame, context);
    CFRelease(frame);
    CFRelease(framesetter);
    CFRelease(path);
}

@end