简单绘画实现 点、线、面

使用绘画  必须在 -（void）drawRect:(CGRect)rect 中使用

例子：

- (void)drawRect:(CGRect)rect
{
    CGContextRef context=UIGraphicsGetCurrentContext();
    
    CGColorSpaceRef colorSpace= CGColorSpaceCreateDeviceRGB();
    
    CGFloat components[]={1.0,0.0,0.0,1.0,
                          0.0,1.0,0.0,1.0,
                          0.0,0.0,0.1,1.0,
                          0.5,0.8,0.2,1.0,
                          0.2,0.8,0.5,1.0,
                          0.6,0.8,0.2,1.0,
                          1.0,1.0,0.5,1.0,
                          0.5,0.2,0.6,1.0,
                          0.8,0.4,0.7,1.0,
                          0.5,0.1,0.3,1.0,
                          0.1,0.1,0.1,1.0,
                          0.6,0.3,0.2,1.0 };
    
    //0-1 输出百分比
    CGFloat locations[]={0.1,0.2,0.3,0.42,0.47,0.56,0.62,0.7,0.8,0.87,0.91,0.95};
    CGGradientRef gradient=CGGradientCreateWithColorComponents(colorSpace ,components, locations, 12);
    
    //矩形
    /*
    CGContextDrawLinearGradient(context, gradient, CGPointMake(50,100), CGPointMake(50, 200), 0);
    */
    
    /*************圆柱*****************/
    CGContextDrawRadialGradient(context, gradient, CGPointMake(100, 100), 50, CGPointMake(200,200), 80, 0);
   
}

在  viewController 中 创建视图

#import "ViewController.h"
#import "GradlentView.h"
@interface ViewController ()
            

@end

@implementation ViewController
            
- (void)viewDidLoad {
    [super viewDidLoad];
    GradlentView *gradlent=[[GradlentView alloc] initWithFrame:self.view.bounds ];
    gradlent.backgroundColor =[UIColor grayColor];
    [self.view addSubview:gradlent];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    
}

@end

改变起始位置和 半径可以得到意想不到的结果哦

结果：