一：效果图如下：

20170112184959106.png

二：代码如下

FBGlowLabel.h

#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

#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

三：使用方法

 FBGlowLabel *glowLabel    = [[FBGlowLabel alloc] initWithFrame:self.view.bounds];
    [self.view addSubview:glowLabel];
    
    glowLabel.text            = @"红红火火";
    glowLabel.textAlignment   = NSTextAlignmentCenter;
    glowLabel.backgroundColor = [UIColor clearColor];
    glowLabel.font            = [UIFont fontWithName:@"Heiti SC" size:40.f];
    glowLabel.textColor       = [[UIColor redColor] colorWithAlphaComponent:0.95f];
    
    glowLabel.glowSize       = 6;
    glowLabel.glowColor      = [UIColor cyanColor];
    
    glowLabel.innerGlowSize  = 3;
    glowLabel.innerGlowColor = [[UIColor blackColor] colorWithAlphaComponent:0.25f];
    
    
    
    FBGlowLabel *glowLabel2    = [[FBGlowLabel alloc] initWithFrame:CGRectMake(50, 500, 300, 40)];
    [self.view addSubview:glowLabel2];
    
    glowLabel2.text            = @"iOS开发 刘成利";
    glowLabel2.textAlignment   = NSTextAlignmentCenter;
    glowLabel2.backgroundColor = [UIColor clearColor];
    glowLabel2.font            = [UIFont fontWithName:@"Heiti SC" size:40.f];
    glowLabel2.textColor       = [[UIColor cyanColor] colorWithAlphaComponent:0.95f];
    
    glowLabel2.glowSize       = 6;
    glowLabel2.glowColor      = [UIColor cyanColor];
    
    glowLabel2.innerGlowSize  = 3;
    glowLabel2.innerGlowColor = [[UIColor blackColor] colorWithAlphaComponent:0.25f];

感谢：
https://blog.csdn.net/IT_liuchengli/article/details/54286752