draw a line by using CGPath [closed]

开发者_C百科 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 10 years ago.

How can I draw a line by using CGPath ?

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As you didn't really specify more than how to draw a line with a path, I'll just give you an example.

Drawing a diagonal line between the top left corner and the bottom right (on iOS) with a path in a UIView's drawRect:

- (void)drawRect:(CGRect)rect { 
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathMoveToPoint(path, NULL, 0, 0);
    CGPathAddLineToPoint(path, NULL, CGRectGetMaxX(rect), CGRectGetMaxY(rect));
    CGPathCloseSubpath(path);
    CGContextAddPath(ctx, path);
    CGContextSetStrokeColorWithColor(ctx,[UIColor whiteColor].CGColor);
    CGContextStrokePath(ctx);
    CGPathRelease(path);
}

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theView.h

#import <UIKit/UIKit.h>

@interface theView : UIView {
}

@end

theView.m

#import "theView.h"

@implementation theView

-(void)drawRect:(CGRect)rect {

    CGContextRef context = UIGraphicsGetCurrentContext(); 
    CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
    CGContextSetLineWidth(context, 2.0);
    CGContextMoveToPoint(context,0,0);
    CGContextAddLineToPoint(context,20,20);
    CGContextStrokePath(context);
}

@end

Create the files mentioned above.
Window-based app: Add new UIView and change its class to theView.
View-based app: Change the UIView class to theView.
Finally hit 'build and run' :)

Result: Red diagonal line.