CAGradientLayer 颜色渐变实现进度条

#import <UIKit/UIKit.h>

@interface TJGradientProgressView : UIView
/**
 *  进度值
 */
@property(nonatomic,assign) CGFloat progressValue;
/**
 *  开始动画
 */
- (void)startAnimating;
/**
 *  停止动画
 */
- (void)stopAnimating;

@end
//
//  TJGradientProgressView.m
//  TJGradientProgressViewDemo
//
//  Created by SNWF on 15/6/17.
//  Copyright (c) 2015年 SNWFMJ. All rights reserved.
//

#import "TJGradientProgressView.h"
@interface TJGradientProgressView ()
{
    CALayer *progressMaskLayer; //进度条蒙版layer图层

}
/**
 *  是否开始动画
 */
@property(nonatomic,assign) BOOL ISAnimating;
@end
@implementation TJGradientProgressView
@synthesize ISAnimating = _ISAnimating;
@synthesize progressValue = _progressValue;

- (instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame])
    {
        /**设置颜色值*/
        CAGradientLayer *gradientLayer = (id)[self layer];
        gradientLayer.startPoint = CGPointMake(0.0, 0.5);
        gradientLayer.endPoint = CGPointMake(1.0, 0.5);

        NSMutableArray *colorArray = [NSMutableArray array];
        for (NSInteger Hue = ; Hue <= ; Hue += ) {
            UIColor *color = [UIColor colorWithHue:1.0*Hue/.f
                                        saturation:1.0
                                        brightness:1.0
                                             alpha:1.0];
            [colorArray addObject:(id)color.CGColor];
        }
        gradientLayer.colors = [NSArray arrayWithArray:colorArray];

        progressMaskLayer = [CALayer layer];
        progressMaskLayer.frame = CGRectMake(, , , frame.size.height);
        progressMaskLayer.backgroundColor = [UIColor blackColor].CGColor;
        gradientLayer.mask = progressMaskLayer;

    }
    return self;
}

- (void)setProgressValue:(CGFloat)progressValue
{
    _progressValue = MIN(1.0, fabs(progressValue));
    [self setNeedsLayout];
}

- (void)layoutSubviews
{
    CGRect maskRect = progressMaskLayer.frame;
    maskRect.size.width = CGRectGetWidth(self.bounds)*_progressValue;
    progressMaskLayer.frame = maskRect;

}
+ (Class)layerClass
{
    return [CAGradientLayer class];
}
- (NSArray *)shiftColors:(NSArray *)colors {

    NSMutableArray *mutable = [colors mutableCopy];
    id last = [mutable lastObject];
    [mutable removeLastObject];
    [mutable insertObject:last atIndex:];
    return [NSArray arrayWithArray:mutable];
}

- (void)performAnimation
{
    CAGradientLayer *layer = (id)[self layer];
    NSArray *fromColors = [layer colors];
    NSArray *toColors = [self shiftColors:fromColors];
    [layer setColors:toColors];

    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"colors"];
    [animation setFromValue:fromColors];
    [animation setToValue:toColors];
    [animation setDuration:0.08];
    [animation setRemovedOnCompletion:YES];
    [animation setFillMode:kCAFillModeForwards];
    [animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]];
    [animation setDelegate:self];
    [layer addAnimation:animation forKey:@"animationGradient"];
}
- (void)animationDidStop:(CAAnimation *)animation finished:(BOOL)flag {

    if (self.ISAnimating) {

        [self performAnimation];
    }
}

- (void)startAnimating {

    if (!self.ISAnimating)
    {

        _ISAnimating = YES;

        [self performAnimation];
    }
}

- (void)stopAnimating {

    if (self.ISAnimating) {

        _ISAnimating = NO;
    }

}

@end
//
//  ViewController.m
//  TJGradientProgressViewDemo
//
//  Created by SNWF on 15/6/17.
//  Copyright (c) 2015年 SNWFMJ. All rights reserved.
//

#import "ViewController.h"
#import "TJGradientProgressView.h"
@interface ViewController ()
{
    TJGradientProgressView *progressView;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    CGRect frame = CGRectMake(, 22.0f, CGRectGetWidth(self.view.bounds), 1.0f);
    progressView = [[TJGradientProgressView alloc] initWithFrame:frame];

    [self.view addSubview:progressView];
    [progressView startAnimating];
    [self simulateProgress];
    //[NSTimer scheduledTimerWithTimeInterval:1.f target:self selector:@selector(testAnimation) userInfo:nil repeats:YES];

}

- (void)testAnimation
{
    progressView.progressValue +=0.1;
    if (progressView.progressValue >=1.0f) {
        [progressView setProgressValue:0.1];
    }

}
- (void)simulateProgress {

    double delayInSeconds = 2.0;
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){

        CGFloat increment = (arc4random() % ) / 10.0f + 0.1;
        CGFloat progress  = progressView.progressValue + increment;
        [progressView setProgressValue:progress];
        if (progress < 1.0) {

            [self simulateProgress];
        }
    });
}

@end