) Diversified display of iPhone strings (nsattributedstring)

Nsattributedstring allows us to diversify the display of a string, but so far as iOS 5 does not seem to support it well, because it is not easy to display (at least not convenient on OS X ).

First, import coretext. Framework and import it to the file to be used:

# Import <coretext/coretext. h>

Create an nsmutableattributedstring:

NSMutableAttributedString *attriString = [[[NSMutableAttributedString alloc] initWithString:@"this is test!"]                                                 autorelease];  

The general creation method is as follows:

// Change the font color of this to red [attristring addattribute :( nsstring *) kctforegroundcolorattributename value :( ID) [uicolor redcolor]. cgcolor range: nsmakerange (0, 4)]; // changes is to yellow [attristring addattriename :( nsstring *) kctforegroundcolorattributename value :( ID) [uicolor yellowcolor]. cgcolor range: nsmakerange (5, 2)]; // change the font of this. The value must be a ctfontref [attristring addattribute :( nsstring *) kctfontattributename value :( ID) ctfontcreatewithname (cfstringref) [uifont boldsystemfontofsize: 14]. fontname, 14, null) range: nsmakerange (0, 4)]; // underline this. You can select [attristring addattribute :( nsstring *) as the value in the specified enumeration *) kctunderlinestyleattributename value :( ID) [nsnumber numberwithint: kctunderlinestyledouble] range: nsmakerange (0, 4)];

Even if the configuration is complete, we can find that nsattributedstring inherits from nsobject and does not support any draw method, so we can only do it ourselves. Write a subclass of uiview (named tview), set the background color to transparent (self. backgroundcolor = [uicolor clearcolor]) in initwithframe, And Then override the drawrect method:

-(void)drawRect:(CGRect)rect{      [super drawRect:rect];            CGContextRef ctx = UIGraphicsGetCurrentContext();      CGContextConcatCTM(ctx, CGAffineTransformScale(CGAffineTransformMakeTranslation(0, rect.size.height), 1.f, -1.f));            CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attriString);      CGMutablePathRef path = CGPathCreateMutable();      CGPathAddRect(path, NULL, rect);            CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), path, NULL);      CFRelease(path);      CFRelease(framesetter);            CTFrameDraw(frame, ctx);      CFRelease(frame);  }  

In the code, we adjusted the CTM (current transformation matrix), because the coordinate system of quartz 2D is different.

Ctframesetter is the creation factory of ctframe. nsattributedstring needs to be drawn to the interface through ctframe. After ctframesetter is obtained, a path is created, and a ctframe is obtained. Finally, the ctframedraw method is used to draw the interface.

If you want to calculate the size required by nsattributedstring, you need to use this API:

Ctframesettersuggestframesizewithconstraints. If you use sizewithfont of nsstring to calculate multiple rows, you cannot control the row spacing in coretext.

Setting the line spacing and line feed mode both sets an attribute: kctparagraphstyleattributename, which is divided into many sub-attributes.

Properties, including

 

• Kctlinebreakbycharwrapping
• Kctparagraphstylespecifierlinespacingadjustment

 

// Section // line break ctparagraphstylesetting linebreakmode; ctlinebreakmode linebreak = kctlinebreakbycharwrapping; // line feed mode linebreakmode. spec = kctparagraphstylespecifierlinebreakmode; linebreakmode. value = & linebreak; linebreakmode. valuesize = sizeof (ctlinebreakmode); // line spacing ctparagraphstylesetting linespacing; cgfloat spacing = 4.0; // specify the linespacing. spec = kctparagraphstylespecifierlinespacingadjustment; linespacing. value = & Spacing; linespacing. valuesize = sizeof (cgfloat); ctparagraphstylesetting settings [] = {linebreakmode, linespacing}; ctparagraphstyleref paragraphstyle = ctparagraphstylecreate (settings, 2 ); // The second parameter is the length of settings [attributedstring addattribute :( nsstring *) kctparagraphstyleattributename value :( ID) paragraphstyle range: nsmakerange (0, attributedstring. length)];

 

----------------------------------------- The boundary -----------------------------------------

This is not the only method, but there is another alternative:

CATextLayer *textLayer = [CATextLayer layer];  textLayer.string = getAttributedString();  textLayer.frame = CGRectMake(0, CGRectGetMaxY(view.frame), 200, 200);  [self.view.layer addSublayer:textLayer];  

Catextlayer can directly support nsattributedstring!

 

<A href = "http://download.csdn.net/detail/zhangao0086/4340376"> Source Code address </a>

 

Original article: http://blog.csdn.net/zhangao0086/article/details/7616385

By yytong