画图+截图+水印

绘图需在- (void)drawRect:(CGRect)rect方法中实现

第一次显示和调用setNeedsDisplay方法时会调用drawRect方法

//圆环

    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(10, 10, 200, 200) cornerRadius:100];

    path.lineWidth=10;

    [[UIColor redColor] set];

    [path stroke];

//扇形

    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(self.bounds.size.width*.5, self.bounds.size.height*.5) radius:100 startAngle:0 endAngle:M_PI_2 clockwise:1];

    [pathaddLineToPoint:CGPointMake(self.bounds.size.width*.5, self.bounds.size.height*.5)];

    [pathclosePath];

    path.lineWidth=10;

    path.lineCapStyle = kCGLineCapRound;

    path.lineJoinStyle = kCGLineCapRound;

    [[UIColor redColor] set];

    [path stroke];

    //文字

    NSString *string = @"hello word hello wordhello wordhello wordhello";

    [string drawInRect:rect withAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:25 weight:5],NSForegroundColorAttributeName:[UIColor redColor]}];

//图片

    UIImage*image = [UIImageimageNamed:@"mineral_force"];

    [image drawInRect:CGRectMake(100, 100, image.size.width, image.size.height)];

//截图3种方式

//第一种

UIImage *image = [UIImage imageWithCGImage:CGImageCreateWithImageInRect(image.CGImage, CGRectMake(50, 50, 100, 100))];

//第二种 

UIGraphicsBeginImageContextWithOptions(CGSizeMake(200, 200), false, 0);

[image drawInRect:rect];//[image drawAtPoint:CGPointZero];

self.imageView.image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

//第三种

UIGraphicsBeginImageContextWithOptions(CGSizeMake(200, 200), false, 0);

    CGContextRef ctx = UIGraphicsGetCurrentContext();

    CGContextAddArc(ctx,100,100,80,0,M_PI*2,1);

    CGContextClip(ctx);

    [imagedrawAtPoint:CGPointMake(0, 0)];

    self.imageView.image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

//屏幕截图

UIGraphicsBeginImageContext(self.view.bounds.size);

    CGContextRef ctx = UIGraphicsGetCurrentContext();

    [[self.view.layer] renderInContext:ctx];

    self.subView.image =UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

//水印

    [imagedrawAtPoint:CGPointZero];

    UIGraphicsBeginImageContextWithOptions(image.size, false, 0);

    NSString*string =@"@copyright";

    //文字水印

    [stringdrawAtPoint:CGPointMake(0, 0) withAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:18 weight:2],NSForegroundColorAttributeName:[UIColor redColor]}];

    //图片水印

    [[UIImage imageNamed:@"mineral_force"] drawAtPoint:CGPointMake(20, 100)];

    self.imageView.image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();