通过改变uiview的layer的frame来实现进度条

#import <UIKit/UIKit.h>

@interface ProgressView : UIView
@property(nonatomic,assign)CGFloat progress;
@property(nonatomic,strong)UIColor *layColor;
@end
#import "ProgressView.h"
@interface ProgressView ()
{
    CALayer *progressLayer;
    
    CGFloat currentViewWidth;//当前view的宽度
}
@end
@implementation ProgressView
@synthesize progress=_progress;
@synthesize layColor=_layColor;

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        progressLayer=[CALayer layer];
        progressLayer.frame=CGRectMake(0, 0, 0, frame.size.height);
        progressLayer.backgroundColor=[UIColor redColor].CGColor;
        [self.layer addSublayer:progressLayer];
        currentViewWidth=frame.size.width;
    }
    return self;
}
-(void)setProgress:(CGFloat)progress
{
    _progress=progress;
    if (progress<=0) {
        progressLayer.frame=CGRectMake(0, 0, 0, self.frame.size.height);
    }
    else if (progress<=1)
    {
        progressLayer.frame=CGRectMake(0, 0, progress*currentViewWidth, self.frame.size.height);
    }
    else
    {
      progressLayer.frame=CGRectMake(0, 0, currentViewWidth, self.frame.size.height);
    }
    
}
-(CGFloat)progress
{
    return _progress;
}
-(void)setLayColor:(UIColor *)layColor
{
    _layColor=layColor;
    self.layer.backgroundColor=layColor.CGColor;
}
-(UIColor *)layColor
{
    return _layColor;
}
@end

#import "ViewController.h"
#import "ProgressView.h"
@interface ViewController ()
@property(nonatomic,strong)ProgressView *progressView;
@property(nonatomic,strong)NSTimer *timer;
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.progressView=[[ProgressView alloc]initWithFrame:CGRectMake(20, 20, 290, 3)];
    [self.view addSubview:self.progressView];
    _timer=[NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(layerAnimation) userInfo:nil repeats:YES];
    
    
}
-(void)layerAnimation
{
    self.progressView.progress=arc4random()%100/100.0f;
    self.progressView.layColor=[UIColor greenColor];
}


@end