【代码笔记】iOS-iOS图片的原生（Graphics）

一，效果图。

二，工程图。

三，代码。

RootViewController.h

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController

@end

RootViewController.m

#import "RootViewController.h"

@interface RootViewController ()

@end

@implementation RootViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    //背景图
    [self addView];

}

#pragma -mark -functions
//背景图
-(void)addView
{
    UIImageView *imageView=[[UIImageView alloc]initWithFrame:CGRectMake(50, 100, 44, 44)];
    imageView.image=[self defaultImage];
    [self.view addSubview:imageView];
}
//图片原生
-(UIImage *)defaultImage {

    static UIImage *defaultImage = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        UIGraphicsBeginImageContextWithOptions(CGSizeMake(20.f, 13.f), NO, 0.0f);

        [[UIColor blackColor] setFill];
        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 0, 20, 1)] fill];
        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 5, 20, 1)] fill];
        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 10, 20, 1)] fill];

        [[UIColor whiteColor] setFill];
        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 1, 20, 2)] fill];
        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 6,  20, 2)] fill];
        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 11, 20, 2)] fill];

        defaultImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();

    });
    return defaultImage;
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}