How to install NSString background cornerRadius on iOS7

Question

I want to install NSString background cornerRadius on iOS7. But NSString has no layer ...

Please tell me how to install NSString background cornerRadius on iOS7?

Example

Answer 1

You can do this using a UITextView with a subclass of NSLayoutManager that overrides -fillBackgroundRectArray:count:forCharacterRange:color: Just a little example:

 @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 

Answer 2

Emmanuel code in swift:

 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

As a complement to @Emmanuel's solution by adding

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

will make it much better.

Answer 4

Upgrade to Swift 3.1 Emmanuel code updated to version 3.1

 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 does not. NSAttributedString has a backgroundColor property that can be used, but without custom rendering, you cannot set the radius of the corner for selecting text fragments.

So you need to write a custom UIView to render the text

Answer 6

An NSString simply defines a line of text. It does not define the properties of how it is displayed. UILabel or UITextView usually used to display text on the screen. However, for the selection behavior that you show in your example, you need to do it yourself. It also changes the text color of the selected text, so you will need to deal with it.

If you created a custom UIView that allows you to draw a blue selection, you can place it behind a UILabel , and you can use NSAttributedString to set the label text where “selected” is selected, the text is white, not black. This is probably the easiest way to do this.