IOS之绘制三角形的实例讲解

- (void)ljTestView {   CGPoint piont1;   piont1.x = 170;   piont1.y = 100;      CGPoint piont2;   piont2.x = 50;   piont2.y = 200;      CGPoint piont3;   piont3.x = 220;   piont3.y = 200;    ljDrawRect *_ljView = [[ljDrawRect alloc]initStartPoint:piont1 middlePoint:piont2 endPoint:piont3 color:[UIColor redColor]];   _ljView.frame = CGRectMake(0, 64, kDEVICEWIDTH, kDEVICEHEIGHT - 64);   _ljView.backgroundColor = [UIColor yellowColor];   [self.view addSubview:_ljView]; } 

#import "ljDrawRect.h"  @interface ljDrawRect () {   CGPoint _startPoint;   CGPoint _middlePoint;   CGPoint _endPoint;   UIColor *_color; } @end  @implementation ljDrawRect  #pragma mark - #pragma mark - method - (instancetype)initStartPoint:(CGPoint)startPoint           middlePoint:(CGPoint)middlePoint            endPoint:(CGPoint)endPoint              color:(UIColor*)color {   self = [super init];      if (self)   {     _startPoint = startPoint;     _middlePoint = middlePoint;     _endPoint = endPoint;     _color = color;     self.backgroundColor = [UIColor clearColor];   }   return self; }  - (void)drawRect:(CGRect)rect {   CGContextRef context = UIGraphicsGetCurrentContext();   CGContextBeginPath(context);//标记   CGContextMoveToPoint(context, _startPoint.x, _startPoint.y);   CGContextAddLineToPoint(context,_middlePoint.x, _middlePoint.y);   CGContextAddLineToPoint(context,_endPoint.x, _endPoint.y);   CGContextClosePath(context);//路径结束标志，不写默认封闭   [_color setFill]; //设置填充色   [_color setStroke];//边框也设置为_color，否则为默认的黑色   CGContextDrawPath(context, kCGPathFillStroke);//绘制路径path }  @end