@interface CustomProgressView : UIView
@property (nonatomic,assign) CGFloat progressValue;
@end

@implementation CustomProgressView
- (void)setProgressValue:(CGFloat)progressValue
{
    _progressValue = progressValue;
    [self setNeedsDisplay];
}
-(void)drawRect:(CGRect)rect
{
    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:self.center radius:100 startAngle:-M_PI_2 endAngle:(_progressValue / 100.0) *(2 * M_PI) - M_PI_2 clockwise:YES];
    [[UIColor redColor] set];
    [path setLineWidth:10];
    [path setLineCapStyle:(kCGLineCapRound)];
    [path stroke];
}

@end

@interface ViewController ()
@property (nonatomic,retain) UISlider *slider;
@property (nonatomic,retain) CustomProgressView *progressView;
@property (nonatomic,retain) UILabel *label;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.progressView = [[CustomProgressView alloc]initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.width)];
    self.progressView.backgroundColor = [UIColor whiteColor];
    
    self.label = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 80, 50)];
    self.label.center = self.progressView.center;
    self.label.textAlignment = NSTextAlignmentCenter;
    [self.progressView addSubview:self.label];
    
    [self.view addSubview:self.progressView];
    
    
    self.slider = [[UISlider alloc]initWithFrame:CGRectMake(10, 500, self.view.frame.size.width - 20, 50)];
    self.slider.minimumValue = 0;
    self.slider.maximumValue = 100;
    [self.slider addTarget:self action:@selector(changeValue:) forControlEvents:(UIControlEventValueChanged)];
    [self.view addSubview:self.slider];
}
- (void)changeValue:(UISlider *)sender
{
    self.progressView.progressValue = sender.value;
    self.label.text = [NSString stringWithFormat:@"%.f%%",sender.value];
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

九.饼状图

@interface PieView ()
@property (nonatomic,retain) NSArray *nums;
@property (nonatomic,assign) NSInteger total;
@end
@implementation PieView
- (NSInteger)total
{
    if (_total == 0) {
        for (int i = 0; i < self.nums.count ; i ++) {
            _total += [self.nums[i] integerValue];
        }
    }
    return _total;
}
- (NSArray *)nums
{
    if (!_nums) {
        self.nums = @[@"10",@"20",@"30",@"40"];
    }
    return _nums;
}
- (void)drawRect:(CGRect)rect
{
    //绘制一个饼图
    CGFloat radius = 150;
    CGFloat startA = 0;
    CGFloat endA = 0;
    
    for (int i = 0; i < self.nums.count; i++) {
        NSNumber *num = self.nums[i];
        startA = endA;
        endA = startA + [num floatValue]/self.total * (2 * M_PI);
        UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:self.center radius:radius startAngle:startA endAngle:endA clockwise:YES];
        [path addLineToPoint:self.center];
        
        CGFloat randRed = arc4random_uniform(256)/255.0;
        CGFloat randGreen = arc4random_uniform(256)/255.0;
        CGFloat randBlue = arc4random_uniform(256)/255.0;
        UIColor *randomColor = [UIColor colorWithRed:randRed green:randGreen blue:randBlue alpha:1];
        [randomColor set];
        
        [path fill];
    }
}

@end

 PieView *pie = [[PieView alloc]initWithFrame:[UIScreen mainScreen].bounds];
    pie.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:pie];

十.柱状图

@interface BarChartView()
@property (nonatomic,retain) NSArray *nums;
@end
@implementation BarChartView
- (NSArray *)nums
{
    if (!_nums) {
        self.nums = @[@"10",@"20",@"30",@"40",@"50",@"60",@"70",@"80"];
    }
    return _nums;
}
- (void)drawRect:(CGRect)rect
{
    //1.获取图形上下文
    CGContextRef ctz = UIGraphicsGetCurrentContext();
    //2.绘制图像
    //设置间距
    CGFloat margin = 30;
    //当柱状图的数量多于5的时候缩小它们的间距
    if (self.nums.count > 5) {
        margin = 10;
    }
    //柱状图的宽度 = （ view的宽度 - 间隔的总宽度 ）/ 柱状图的个数
    CGFloat width = (rect.size.width - (self.nums.count + 1) *margin) / self.nums.count;
    for (int i = 0; i < self.nums.count; i++) {
        
        //求出 每一个数字所占的比例
        CGFloat num = [self.nums[i] floatValue]/100;
        //起点位置
        CGFloat x = margin + (width + margin) * i ;
        CGFloat y = rect.size.height * (1 - num);
        CGFloat height = rect.size.height * num;
        
        CGRect rectA = CGRectMake(x, y, width, height);
        CGContextAddRect(ctz, rectA);
        
        CGFloat randRed = arc4random_uniform(256)/255.0;
        CGFloat randGreen = arc4random_uniform(256)/255.0;
        CGFloat randBlue = arc4random_uniform(256)/255.0;
        UIColor *randomColor = [UIColor colorWithRed:randRed green:randGreen blue:randBlue alpha:1];
        
        [randomColor set];
        //渲染
        CGContextFillPath(ctz);
       
    }
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code
}
*/

@end

 BarChartView *view = [[BarChartView alloc]initWithFrame:[UIScreen mainScreen].bounds];
    view.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:view];

绘制文字和图片的时候，是不用去获取图像上下文的