支持辉光效果的Label

效果

源码

https://github.com/YouXianMing/UI-Component-Collection 中的 FBGlowLabel

//
//  FBGlowLabel.h
//
//  Created by YouXianMing on 16/8/3.
//  Copyright © 2016年 YouXianMing. All rights reserved.
//
//  https://github.com/lyokato/fbglowlabel
//

#import <UIKit/UIKit.h>

@interface FBGlowLabel : UILabel

/**
 *  Glow size, default is 0.f.
 */
@property (nonatomic) CGFloat glowSize;

/**
 *  Glow color, default is clear color.
 */
@property (nonatomic, strong) UIColor *glowColor;

/**
 *  Inner glow size, default is 0.f.
 */
@property (nonatomic) CGFloat innerGlowSize;

/**
 *  Inner glow color, default is clear color.
 */
@property (nonatomic, strong) UIColor *innerGlowColor;

@end

//
//  FBGlowLabel.m
//
//  Created by YouXianMing on 16/8/3.
//  Copyright © 2016年 YouXianMing. All rights reserved.
//

#import "FBGlowLabel.h"

@implementation FBGlowLabel

- (id)initWithFrame:(CGRect)frame {

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

        [self setup];
    }

    return self;
}

- (id)initWithCoder:(NSCoder *)coder {

    if (self = [super initWithCoder:coder]) {

        [self setup];
    }

    return self;
}

- (void)setup {

    self.glowSize       = 0.0f;
    self.glowColor      = [UIColor clearColor];

    self.innerGlowSize  = 0.0f;
    self.innerGlowColor = [UIColor clearColor];
}

- (void)drawTextInRectForIOS7:(CGRect)rect {

    CGContextRef ctx = UIGraphicsGetCurrentContext();

    UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0.0);

    [super drawTextInRect:rect];
    UIImage *textImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    CGContextSaveGState(ctx);

    if (_glowSize > 0) {

        CGContextSetShadow(ctx, CGSizeZero, _glowSize);
        CGContextSetShadowWithColor(ctx, CGSizeZero, _glowSize, _glowColor.CGColor);
    }

    [textImage drawAtPoint:rect.origin];
    CGContextRestoreGState(ctx);

    if (_innerGlowSize > 0) {

        UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0.0);
        CGContextRef ctx2 = UIGraphicsGetCurrentContext();
        CGContextSaveGState(ctx2);
        CGContextSetFillColorWithColor(ctx2, [UIColor blackColor].CGColor);
        CGContextFillRect(ctx2, rect);
        CGContextTranslateCTM(ctx2, 0.0, rect.size.height);
        CGContextScaleCTM(ctx2, 1.0, -1.0);
        CGContextClipToMask(ctx2, rect, textImage.CGImage);
        CGContextClearRect(ctx2, rect);
        CGContextRestoreGState(ctx2);

        UIImage *inverted = UIGraphicsGetImageFromCurrentImageContext();
        CGContextClearRect(ctx2, rect);

        CGContextSaveGState(ctx2);
        CGContextSetFillColorWithColor(ctx2, _innerGlowColor.CGColor);
        CGContextSetShadowWithColor(ctx2, CGSizeZero, _innerGlowSize, _innerGlowColor.CGColor);
        [inverted drawAtPoint:CGPointZero];
        CGContextTranslateCTM(ctx2, 0.0, rect.size.height);
        CGContextScaleCTM(ctx2, 1.0, -1.0);
        CGContextClipToMask(ctx2, rect, inverted.CGImage);
        CGContextClearRect(ctx2, rect);
        CGContextRestoreGState(ctx2);

        UIImage *innerShadow = UIGraphicsGetImageFromCurrentImageContext();

        UIGraphicsEndImageContext();
        [innerShadow drawAtPoint:rect.origin];
    }
}

- (void)drawTextInRectForIOS6:(CGRect)rect {

    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextSaveGState(ctx);

    if (self.glowSize > 0) {

        CGContextSetShadow(ctx, CGSizeZero, _glowSize);
        CGContextSetShadowWithColor(ctx, CGSizeZero, _glowSize, _glowColor.CGColor);
    }

    [super drawTextInRect:rect];
    CGContextRestoreGState(ctx);

    if (_innerGlowSize > 0) {

        UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0.0);

        CGContextRef ctx2 = UIGraphicsGetCurrentContext();
        [super drawTextInRect:rect];

        UIImage *textImage = UIGraphicsGetImageFromCurrentImageContext();
        CGContextClearRect(ctx2, rect);

        CGContextSaveGState(ctx2);
        CGContextSetFillColorWithColor(ctx2, [UIColor blackColor].CGColor);
        CGContextFillRect(ctx2, rect);
        CGContextTranslateCTM(ctx2, 0.0, rect.size.height);
        CGContextScaleCTM(ctx2, 1.0, -1.0);
        CGContextClipToMask(ctx2, rect, textImage.CGImage);
        CGContextClearRect(ctx2, rect);
        CGContextRestoreGState(ctx2);

        UIImage *inverted = UIGraphicsGetImageFromCurrentImageContext();
        CGContextClearRect(ctx2, rect);

        CGContextSaveGState(ctx2);
        CGContextSetFillColorWithColor(ctx2, _innerGlowColor.CGColor);
        CGContextSetShadowWithColor(ctx2, CGSizeZero, _innerGlowSize, _innerGlowColor.CGColor);
        [inverted drawAtPoint:CGPointZero];
        CGContextTranslateCTM(ctx2, 0.0, rect.size.height);
        CGContextScaleCTM(ctx2, 1.0, -1.0);
        CGContextClipToMask(ctx2, rect, inverted.CGImage);
        CGContextClearRect(ctx2, rect);
        CGContextRestoreGState(ctx2);

        UIImage *innerShadow = UIGraphicsGetImageFromCurrentImageContext();

        UIGraphicsEndImageContext();
        [innerShadow drawAtPoint:rect.origin];
    }
}

- (void)drawTextInRect:(CGRect)rect {

    if (self.text == nil || self.text.length == 0) {

        return;
    }

    if ([[[UIDevice currentDevice] systemVersion] compare:@"7.0" options:NSNumericSearch] != NSOrderedAscending) {

        [self drawTextInRectForIOS7:rect];

    } else {

        [self drawTextInRectForIOS6:rect];
    }
}

@end

//
//  ViewController.m
//  FBGlowLabel
//
//  Created by YouXianMing on 16/8/3.
//  Copyright © 2016年 YouXianMing. All rights reserved.
//

#import "ViewController.h"
#import "FBGlowLabel.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    self.view.backgroundColor = [UIColor blackColor];

    FBGlowLabel *glowLabel    = [[FBGlowLabel alloc] initWithFrame:self.view.bounds];
    [self.view addSubview:glowLabel];

    glowLabel.text            = @"壹擊必殺";
    glowLabel.textAlignment   = NSTextAlignmentCenter;
    glowLabel.backgroundColor = [UIColor clearColor];
    glowLabel.font            = [UIFont fontWithName:@"Heiti SC" size:40.f];
    glowLabel.textColor       = [[UIColor cyanColor] colorWithAlphaComponent:0.95f];

    glowLabel.glowSize       = 6;
    glowLabel.glowColor      = [UIColor cyanColor];

    glowLabel.innerGlowSize  = 3;
    glowLabel.innerGlowColor = [[UIColor blackColor] colorWithAlphaComponent:0.25f];
}

@end