Question

我想在iOS7上设置NSString的背景cornerRadius。但是，NSString没有图层......

请告诉我，如何在iOS7上设置NSString的背景cornerRadius？

示例

Answer 1

您可以使用UITextView，其子类为NSLayoutManager来覆盖-fillBackgroundRectArray:count:forCharacterRange:color:。只是一点点示例如何：

@implementation ViewController
- (void)viewDidLoad
{
    [super viewDidLoad];

    // setup text handling
    NSTextStorage *textStorage = [[NSTextStorage alloc] initWithString:@"Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda."];

    // use our subclass of NSLayoutManager
    MyLayoutManager *textLayout = [[MyLayoutManager alloc] init];

    [textStorage addLayoutManager:textLayout];

    NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:self.view.bounds.size];

    [textLayout addTextContainer:textContainer];
    UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(0,20,self.view.bounds.size.width,self.view.bounds.size.height-20)
                                               textContainer:textContainer];
    [self.view addSubview:textView];

    // set some background color to our text
    [textView.textStorage setAttributes:[NSDictionary dictionaryWithObject:[UIColor blueColor] forKey:NSBackgroundColorAttributeName] range:NSMakeRange(22, textView.text.length - 61)];
}
@end

@interface MyLayoutManager : NSLayoutManager
@end

- (void)fillBackgroundRectArray:(const CGRect *)rectArray count:(NSUInteger)rectCount forCharacterRange:(NSRange)charRange color:(UIColor *)color
{
     CGFloat halfLineWidth = 4.; // change this to change corners radius

     CGMutablePathRef path = CGPathCreateMutable();

     if (rectCount == 1
         || (rectCount == 2 && (CGRectGetMaxX(rectArray[1]) < CGRectGetMinX(rectArray[0])))
        )
    {
        // 1 rect or 2 rects without edges in contact

         CGPathAddRect(path, NULL, CGRectInset(rectArray[0], halfLineWidth, halfLineWidth));
         if (rectCount == 2)
            CGPathAddRect(path, NULL, CGRectInset(rectArray[1], halfLineWidth, halfLineWidth));
    }
     else
    {
        // 2 or 3 rects
         NSUInteger lastRect = rectCount - 1;

         CGPathMoveToPoint(path, NULL, CGRectGetMinX(rectArray[0]) + halfLineWidth, CGRectGetMaxY(rectArray[0]) + halfLineWidth);

         CGPathAddLineToPoint(path, NULL, CGRectGetMinX(rectArray[0]) + halfLineWidth, CGRectGetMinY(rectArray[0]) + halfLineWidth);
         CGPathAddLineToPoint(path, NULL, CGRectGetMaxX(rectArray[0]) - halfLineWidth, CGRectGetMinY(rectArray[0]) + halfLineWidth);

         CGPathAddLineToPoint(path, NULL, CGRectGetMaxX(rectArray[0]) - halfLineWidth, CGRectGetMinY(rectArray[lastRect]) - halfLineWidth);
         CGPathAddLineToPoint(path, NULL, CGRectGetMaxX(rectArray[lastRect]) - halfLineWidth, CGRectGetMinY(rectArray[lastRect]) - halfLineWidth);

         CGPathAddLineToPoint(path, NULL, CGRectGetMaxX(rectArray[lastRect]) - halfLineWidth, CGRectGetMaxY(rectArray[lastRect]) - halfLineWidth);
         CGPathAddLineToPoint(path, NULL, CGRectGetMinX(rectArray[lastRect]) + halfLineWidth, CGRectGetMaxY(rectArray[lastRect]) - halfLineWidth);

         CGPathAddLineToPoint(path, NULL, CGRectGetMinX(rectArray[lastRect]) + halfLineWidth, CGRectGetMaxY(rectArray[0]) + halfLineWidth);

         CGPathCloseSubpath(path);
    }

    [color set]; // set fill and stroke color

     CGContextRef ctx = UIGraphicsGetCurrentContext();
     CGContextSetLineWidth(ctx, halfLineWidth * 2.);
     CGContextSetLineJoin(ctx, kCGLineJoinRound);

     CGContextAddPath(ctx, path);
     CGPathRelease(path);

     CGContextDrawPath(ctx, kCGPathFillStroke);
}
@end

sample image

Answer 2

Emmanuel在swift中的代码：

class TagLayoutManager : NSLayoutManager { override func fillBackgroundRectArray(rectArray: UnsafePointer<CGRect>, count rectCount: Int, forCharacterRange charRange: NSRange, color: UIColor) { let cornerRadius:CGFloat = 3.0 let path = CGPathCreateMutable() if rectCount == 1 || (rectCount == 2 && (CGRectGetMaxX(rectArray[1]) < CGRectGetMaxX(rectArray[0]))) { CGPathAddRect(path, nil, CGRectInset(rectArray[0], cornerRadius, cornerRadius)) if rectCount == 2 { CGPathAddRect(path, nil, CGRectInset(rectArray[1], cornerRadius, cornerRadius)) } } else { let lastRect = rectCount - 1 CGPathMoveToPoint(path, nil, CGRectGetMinX(rectArray[0]) + cornerRadius, CGRectGetMaxY(rectArray[0]) + cornerRadius); CGPathAddLineToPoint(path, nil, CGRectGetMinX(rectArray[0]) + cornerRadius, CGRectGetMinY(rectArray[0]) + cornerRadius); CGPathAddLineToPoint(path, nil, CGRectGetMaxX(rectArray[0]) - cornerRadius, CGRectGetMinY(rectArray[0]) + cornerRadius); CGPathAddLineToPoint(path, nil, CGRectGetMaxX(rectArray[0]) - cornerRadius, CGRectGetMinY(rectArray[lastRect]) - cornerRadius); CGPathAddLineToPoint(path, nil, CGRectGetMaxX(rectArray[lastRect]) - cornerRadius, CGRectGetMinY(rectArray[lastRect]) - cornerRadius); CGPathAddLineToPoint(path, nil, CGRectGetMaxX(rectArray[lastRect]) - cornerRadius, CGRectGetMaxY(rectArray[lastRect]) - cornerRadius); CGPathAddLineToPoint(path, nil, CGRectGetMinX(rectArray[lastRect]) + cornerRadius, CGRectGetMaxY(rectArray[lastRect]) - cornerRadius); CGPathAddLineToPoint(path, nil, CGRectGetMinX(rectArray[lastRect]) + cornerRadius, CGRectGetMaxY(rectArray[0]) + cornerRadius); CGPathCloseSubpath(path); } color.set() let ctx = UIGraphicsGetCurrentContext() CGContextSetLineWidth(ctx, cornerRadius * 2.0) CGContextSetLineJoin(ctx, .Round) CGContextAddPath(ctx, path) CGContextDrawPath(ctx, .FillStroke) } }

Answer 3

作为@ Emmanuel解决方案的补充，添加

CGContextSetAllowsAntialiasing(ctx, YES);
CGContextSetShouldAntialias(ctx, YES);

会让它看起来更好。

Answer 4

更新到Swift 3.1 Emmanuel的代码在swift中更新到3.1版

class TagLayoutManager: NSLayoutManager {

override func fillBackgroundRectArray(_ rectArray: UnsafePointer<CGRect>, count rectCount: Int, forCharacterRange charRange: NSRange, color: UIColor) {

    let cornerRadius:CGFloat = 5
    let path = CGMutablePath.init()




    if rectCount == 1 || (rectCount == 2 && (rectArray[1].maxX < rectArray[0].maxX)) {

        path.addRect(rectArray[0].insetBy(dx: cornerRadius, dy: cornerRadius))

        if rectCount == 2 {
            path.addRect(rectArray[1].insetBy(dx: cornerRadius, dy: cornerRadius))
        }

    } else {

        let lastRect = rectCount - 1

        path.move(to: CGPoint(x: rectArray[0].minX + cornerRadius, y: rectArray[0].maxY + cornerRadius))

        path.addLine(to: CGPoint(x: rectArray[0].minX + cornerRadius, y: rectArray[0].minY + cornerRadius))
        path.addLine(to: CGPoint(x: rectArray[0].maxX - cornerRadius, y: rectArray[0].minY + cornerRadius))

        path.addLine(to: CGPoint(x: rectArray[0].maxX - cornerRadius, y: rectArray[lastRect].minY - cornerRadius))
        path.addLine(to: CGPoint(x: rectArray[lastRect].maxX - cornerRadius, y: rectArray[lastRect].minY - cornerRadius))

        path.addLine(to: CGPoint(x: rectArray[lastRect].maxX - cornerRadius, y: rectArray[lastRect].maxY - cornerRadius))
        path.addLine(to: CGPoint(x: rectArray[lastRect].minX + cornerRadius, y: rectArray[lastRect].maxY - cornerRadius))

        path.addLine(to: CGPoint(x: rectArray[lastRect].minX + cornerRadius, y: rectArray[0].maxY + cornerRadius))

        path.closeSubpath()

    }

    color.set()

    let ctx = UIGraphicsGetCurrentContext()
    ctx!.setLineWidth(cornerRadius * 2.0)
    ctx!.setLineJoin(.round)

    ctx!.setAllowsAntialiasing(true)
    ctx!.setShouldAntialias(true)

    ctx!.addPath(path)
    ctx!.drawPath(using: .fillStroke)
}
}

Answer 5

NSString没有。 NSAttributedString具有可以使用的backgroundColor属性，但是没有自定义渲染，您将无法为选择的文本片段设置角半径。

因此，您需要编写自定义UIView来呈现文本

Answer 6

NSString只定义一个文本字符串。它没有定义渲染方式的属性。要在屏幕上显示文字，通常会使用UILabel或UITextView。但是，对于您在示例中显示的选择行为，您需要自己进行绘制。此外，它正在更改所选文本的文本颜色，因此您需要自己处理。

如果您创建了一个允许您绘制蓝色选区的自定义UIView，则可以将其放在UILabel后面，并且您可以使用NSAttributedString来设置“选定”文本为白色而不是黑色的标签。这可能是最简单的方法。

如何在iOS7上设置NSString的背景cornerRadius

6 个答案: