*重新定義UIView 並在drawRect:(CGRect) rect;中繪制

1.繪制路徑

 

 

_context=UIGraphicsGetCurrentContext();

    CGMutablePathRef path=CGPathCreateMutable();
    
    CGPathMoveToPoint(path, NULL, 50, 50);
    CGPathAddLineToPoint(path, NULL, 150, 150);
    CGPathAddLineToPoint(path, NULL, 50, 150);
    CGPathCloseSubpath(path);
    
    CGContextAddPath(_context, path);
    
    CGFloat myColor[4]={1.0f,1.0f,0,1.0f};
    CGContextSetFillColor(_context,myColor);
    CGContextSetStrokeColor(_context, myColor);
    CGContextSetShouldAntialias(_context, NO);
    CGContextSetLineWidth(_context, 15.0);
    CGContextSetLineJoin(_context, kCGLineJoinRound);
    
    CGContextDrawPath(_context, kCGPathStroke);
    
    CGPathRelease(path);
    CGContextRelease(_context);

2.繪制矩形

 

 

    CGRect rect2=CGRectMake(0, 0, 200, 200);
    CGContextSetStrokeColorWithColor(_context, [UIColor redColor].CGColor);
    CGContextSetLineWidth(_context, 2.0);
    CGContextStrokeRect(_context, rect2);

3.繪制漸變

 

 

_context=UIGraphicsGetCurrentContext();
    
    //顏色模式
    CGColorSpaceRef colorSpace=CGColorSpaceCreateDeviceRGB();
    
    //構建顏色值
    NSArray *colors=@[(__bridge id)[UIColor redColor].CGColor,(__bridge id)[UIColor greenColor].CGColor];
    //顏色點的位置
    CGFloat location[2]={0,1};
    
    //設置漸變模式
    CGGradientRef gradient=CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef)colors,location);
    
    CGContextSaveGState(_context);
    
    CGRect rect2=CGRectMake(0, 0, 150, 150);
    //繪制區域
    CGContextAddRect(_context, rect2);
    //區域裁剪
    CGContextClip(_context);
    
    //裁剪位置
    CGContextDrawLinearGradient(_context, gradient, CGPointMake(0, 0), CGPointMake(150, 150),kCGGradientDrawsAfterEndLocation);
    
    CGContextRestoreGState(_context);
    
    //釋放資源
    CGColorSpaceRelease(colorSpace);
    CGGradientRelease(gradient);
    
    
    CGContextRelease(_context);

4.繪制文字

 

 

NSString *str=[UIFont fontWithName:@"Gill Sans" size:30];
    NSString *drawText=@"hello !";
    [drawText drawAtPoint:CGPointMake(30, 100) withFont:str];

5.繪制圖片

 

 

 

UIImage *image=[UIImage imageNamed:@"頭像2.png"];
    
    [image drawAtPoint:CGPointMake(30, 30)];
    
    CGImageRelease([image CGImage]);

6.貝塞爾曲線繪制

 

 

    //繪制線
    UIBezierPath *path=[UIBezierPath bezierPath];
    [path moveToPoint:CGPointMake(30, 30)];
    [path addLineToPoint:CGPointMake(30, 120)];
    [path addLineToPoint:CGPointMake(120, 120)];
    [path closePath];

    //繪制圓
    UIBezierPath *path=[UIBezierPath bezierPathWithArcCenter:CGPointMake(100, 100) radius:100.0 startAngle:0 endAngle:180 clockwise:YES];
    //繪制矩形
    UIBezierPath *path=[UIBezierPath bezierPathWithRect:CGRectMake(20, 20, 150, 150)];
    
    //繪制橢圓
    UIBezierPath *path=[UIBezierPath bezierPathWithOvalInRect:CGRectMake(10, 10, 120, 60)];
    //設置顏色
    [[UIColor redColor]set];
    
    path.lineWidth=5;
    [path fill];
    [[UIColor yellowColor]set];
    [path stroke];

7.保存繪制環境，在繪制過程中 屬性可能需要保存到棧中 這時候調用CGContextSaveGState進行保存，

 

並在需要的時候通過CGContextRestoreGState進行恢復。