iOS开发——绘图电池按百分比显示

　　1、在DrawLine.h文件中提供了一个改变电池电量数值的接口

// DrawLine.h

// Demo-draw2

// Created by yyt on 16/5/11.

#import <UIKit/UIKit.h>

@interface DrawLine : UIView

@property(nonatomic,assign) NSInteger currentNum;

@end

　　2、在DrawLine.m文件中

// DrawLine.m

// Demo-draw2

// Created by yyt on 16/5/11.

#import "DrawLine.h"

@implementation DrawLine

- (void)drawRect:(CGRect)rect {

CGContextRef bgContextRef = UIGraphicsGetCurrentContext();

CGRect frame = CGRectMake(10, 10, 40, 20);

CGContextAddRect(bgContextRef, frame);

CGContextSetLineWidth(bgContextRef, 2);

[commonBgColor setStroke];

CGContextStrokePath(bgContextRef);

CGContextMoveToPoint(bgContextRef, 50, 20);

CGContextAddLineToPoint(bgContextRef, 54, 20);

CGContextSetLineWidth(bgContextRef, 6);

CGContextStrokePath(bgContextRef);

CGContextMoveToPoint(bgContextRef, 10, 20);

CGContextAddLineToPoint(bgContextRef, 10+_currentNum*40/100, 20);

CGContextSetLineWidth(bgContextRef, 20);

CGContextStrokePath(bgContextRef);

}

@end

　　3、在需要用的地方ViewController.m文件中

　　我这里是写了个死数据，真正做项目的话，就需要在电量值发生改变的时候，修改currentNum值，然后setNeedsDisplay一下。

// ViewController.m

// Demo-draw2

// Created by yyt on 16/5/11.

#import "ViewController.h"

#import "DrawLine.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

self.view.backgroundColor = [UIColor lightGrayColor];

DrawLine *lineView = [[DrawLine alloc] initWithFrame:CGRectMake(100, 100, 200, 200)];

lineView.backgroundColor = [UIColor whiteColor];

　 lineView.currentNum = 87;

[self.view addSubview:lineView];

}

@end