UILabel光暈效果

- (instancetype)initWithFrame:(CGRect)frame{

    if (self = [super initWithFrame:frame]) {

        _red = 0;

        _green = 0.5;

        _blue = 1.0;

    }

    return self;

}

- (void)drawTextInRect:(CGRect)rect{

    CGSize textShadowOffest = CGSizeMake(0, 0);

    CGFloat textColorValues[] = {_red, _green, _blue, 1.0};

    

    CGContextRef ctx = UIGraphicsGetCurrentContext();

    CGContextSaveGState(ctx);

    

    CGContextSetShadow(ctx, textShadowOffest, 4);

    CGColorSpaceRef textColorSpace = CGColorSpaceCreateDeviceRGB();

    CGColorRef textColor = CGColorCreate(textColorSpace, textColorValues);

    CGContextSetShadowWithColor(ctx, textShadowOffest, 4, textColor);

    

    [super drawTextInRect:rect];

    

    CGColorRelease(textColor);

    CGColorSpaceRelease(textColorSpace);

    

    CGContextRestoreGState(ctx);

}

http://my.oschina.net/joanfen/blog/145184