iOS-CALayer实现简单进度条

/**
 *  用CALayer定制下载进度条控件
 *  1.单独创建出CALayer
 *  2.直接修改CALayer的frame值，执行隐式动画，实现进度条效果
 *  3.用定时器（NSTimer）模拟网络下载时提供的百分比数据
 *  4.将CALayer封装进UIView子类中定制进度条控件

 */

 自定义一个UIView,创建CALayer

#import <UIKit/UIKit.h>

@interface WJProgressView : UIView

@property (nonatomic,assign)CGFloat progress;//进度参数取值范围0~100
@property (nonatomic,strong)UIColor *progressColor;//颜色

@end

#import "WJProgressView.h"

@interface WJProgressView ()

@property (nonatomic,strong)CALayer *progressLayer;
@property (nonatomic,assign)CGFloat currentViewWidth;

@end

@implementation WJProgressView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.progressLayer = [CALayer layer];
        self.backgroundColor = [UIColor grayColor];
        self.progressLayer.backgroundColor = [UIColor redColor].CGColor;
        self.progressLayer.frame = CGRectMake(0, 0, 0, frame.size.height);
        [self.layer addSublayer:self.progressLayer];
        //储存当前view的宽度值
        self.currentViewWidth = frame.size.width;
    }
    return self;
}

#pragma mark - 重写setter,getter方法

@synthesize progress = _progress;
- (void)setProgress:(CGFloat)progress {
    _progress = progress;
    if (progress <= 0) {
        self.progressLayer.frame = CGRectMake(0, 0, 0, self.frame.size.height);
    }else if (progress <= 1) {
        self.progressLayer.frame = CGRectMake(0, 0, progress *self.currentViewWidth, self.frame.size.height);
    }else {
        self.progressLayer.frame = CGRectMake(0, 0, self.currentViewWidth, self.frame.size.height);
    }
}

- (CGFloat)progress {
    return _progress;
}

@synthesize progressColor = _progressColor;
- (void)setProgressColor:(UIColor *)progressColor {
    _progressColor = progressColor;
    self.progressLayer.backgroundColor = progressColor.CGColor;
}

- (UIColor *)progressColor {
    return _progressColor;
}

 向上面那样封装的话，只需改变progress进度属性就能改变CALayer的frame(隐式动画)

self.progressView.progress = arc4random()%100/100.f;

 效果图: