//
//  DrawView.m
//  01-基本線條繪制(畫線)(熟悉)
//
//  Created by 李亮 on 2016/11/30.
//  Copyright ? 2016年 www.thelast.com. All rights reserved.
//

#import "DrawView.h"

@implementation DrawView

- (void)drawRect:(CGRect)rect {
 
    [self drawCurve];
}
//曲線
- (void)drawCurve{
    
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    
    UIBezierPath * path = [UIBezierPath bezierPath];
    
    [path moveToPoint:CGPointMake(50, 200)];
    
    CGPoint p1 = CGPointMake(175, 200);
    CGPoint p2 = CGPointMake(300, 100);
    
    [path addCurveToPoint:CGPointMake(300, 100) controlPoint1:p1 controlPoint2:p2];
    
    [[UIColor yellowColor] set];
//    [path addQuadCurveToPoint:CGPointMake(300, 200) controlPoint:CGPointMake(175, 100)];
    
    CGContextAddPath(ctx, path.CGPath);
    CGContextStrokePath(ctx);
}
//鏈接線
- (void)drawlinkLines{
    
    //獲取上下方
    CGContextRef contextRef = UIGraphicsGetCurrentContext();
    
    //生成路徑
    UIBezierPath * path = [UIBezierPath bezierPath];
    
    CGPoint startP = CGPointMake(50, 200);
    //第一條
    [path moveToPoint:startP];
    [path addLineToPoint:CGPointMake(200, 200)];
    //鏈接第二條
    [path addLineToPoint:CGPointMake(200, 100)];
    //鏈接第3條
    [path addLineToPoint:CGPointMake(50, 100)];
    //鏈接第4條
    [path addLineToPoint:CGPointMake(50, 200)];
    
    //設置線寬
    CGContextSetLineWidth(contextRef, 10);
    //鏈接角
    CGContextSetLineJoin(contextRef, kCGLineJoinRound);
    //顏色
    [[UIColor redColor] set];
    //設置線的頂角樣式
    CGContextSetLineCap(contextRef, kCGLineCapRound);
    
    CGContextAddPath(contextRef, path.CGPath);
    //關閉上下文
//    CGContextFillPath(contextRef);
    CGContextStrokePath(contextRef);
}
//畫多條線
- (void)drawLines{
    
    //獲取上下方
    CGContextRef contextRef = UIGraphicsGetCurrentContext();
    
    //生成路徑
    UIBezierPath * path = [UIBezierPath bezierPath];
    
    CGPoint startP = CGPointMake(50, 200);
    //第一條
    [path moveToPoint:startP];
    [path addLineToPoint:CGPointMake(200, 200)];
    
    //第二條
    [path moveToPoint:CGPointMake(50, 100)];
    [path addLineToPoint:CGPointMake(200, 100)];
    
    CGContextAddPath(contextRef, path.CGPath);
    //關閉上下文
    CGContextStrokePath(contextRef);
}
//畫一條線
- (void)drawLine{
    //獲取上下方
    CGContextRef contextRef = UIGraphicsGetCurrentContext();
    
    //生成路徑
    UIBezierPath * path = [UIBezierPath bezierPath];
    
    CGPoint startP = CGPointMake(50, 200);
    [path moveToPoint:startP];
    
    [path addLineToPoint:CGPointMake(200, 200)];
    
    CGContextAddPath(contextRef, path.CGPath);
    //關閉上下文
    CGContextStrokePath(contextRef);
}
@end

需要注意的是

CGPoint p1 = CGPointMake(175, 200);
CGPoint p2 = CGPointMake(300, 100);
[path addCurveToPoint:CGPointMake(300, 100) controlPoint1:p1 controlPoint2:p2]; 
[path addQuadCurveToPoint:CGPointMake(300, 200) controlPoint:CGPointMake(175, 100)];

這倆個方法，一個是設置一個點畫曲線，另外一個是設置倆個點畫曲線，有什么呢？
比如我上方給的倆個坐標點，如果p2給CGPointMake(300, 200);那么曲線會向下彎曲。如果給CGPointMake(300, 100)，則會往上彎曲。如圖

WechatIMG3.jpeg

WechatIMG5.jpeg