//下面是用coreText 實現

//UILabel中對應的點Pt在UILabel中所有的字體屬性

-(NSDictionary*)textAttributesAtPoint:(CGPoint)pt withLabel:(UILabel*)lab

{

// Locate the attributes of the text within the label at the specified point

NSDictionary* dictionary =nil;

// First, create a CoreText framesetter

CTFramesetterRefframesetter =CTFramesetterCreateWithAttributedString((__bridgeCFAttributedStringRef)lab.attributedText);

CGMutablePathRefframePath =CGPathCreateMutable();

CGPathAddRect(framePath,NULL,CGRectMake(0,0, lab.frame.size.width, lab.frame.size.height));

// Get the frame that will do the rendering.

CFRangecurrentRange =CFRangeMake(0,0);

CTFrameRefframeRef =CTFramesetterCreateFrame(framesetter, currentRange, framePath,NULL);

CGPathRelease(framePath);

// Get each of the typeset lines

NSArray*lines = (__bridgeid)CTFrameGetLines(frameRef);

CFIndexlinesCount = [linescount];

CGPoint*lineOrigins = (CGPoint*)malloc(sizeof(CGPoint) * linesCount);

CTFrameGetLineOrigins(frameRef,CFRangeMake(0, linesCount), lineOrigins);

CTLineRefline =NULL;

CGPointlineOrigin =CGPointZero;

// Correct each of the typeset lines (which have origin (0,0)) to the correct orientation (typesetting offsets from the bottom of the frame)

CGFloatbottom = lab.frame.size.height;

for(CFIndexi =0; i < linesCount; ++i) {

lineOrigins[i].y= lab.frame.size.height- lineOrigins[i].y;

bottom = lineOrigins[i].y;

}

// Offset the touch point by the amount of space between the top of the label frame and the text

pt.y-= (lab.frame.size.height- bottom)/2;

// Scan through each line to find the line containing the touch point y position

for(CFIndexi =0; i < linesCount; ++i) {

line = (__bridgeCTLineRef)[linesobjectAtIndex:i];

lineOrigin = lineOrigins[i];

CGFloatdescent, ascent;

CGFloatwidth =CTLineGetTypographicBounds(line, &ascent, &descent,nil);

if(pt.y< (floor(lineOrigin.y) +floor(descent))) {

// Cater for text alignment set in the label itself (not in the attributed string)

if(lab.textAlignment==NSTextAlignmentCenter) {

pt.x-= (lab.frame.size.width- width)/2;

}elseif(lab.textAlignment==NSTextAlignmentRight) {

pt.x-= (lab.frame.size.width- width);

}

// Offset the touch position by the actual typeset line origin. pt is now the correct touch position with the line bounds

pt.x-= lineOrigin.x;

pt.y-= lineOrigin.y;

// Find the text index within this line for the touch position

CFIndexi =CTLineGetStringIndexForPosition(line, pt);

// Iterate through each of the glyph runs to find the run containing the character index

NSArray* glyphRuns = (__bridgeid)CTLineGetGlyphRuns(line);

CFIndexrunCount = [glyphRunscount];

for(CFIndexrun=0; run

CTRunRefglyphRun = (__bridgeCTRunRef)[glyphRunsobjectAtIndex:run];

CFRangerange =CTRunGetStringRange(glyphRun);

if(i >= range.location&& i<= range.location+range.length) {

dictionary = (__bridgeNSDictionary*)CTRunGetAttributes(glyphRun);

break;

}

}

if(dictionary) {

break;

}

}

}

free(lineOrigins);

CFRelease(frameRef);

CFRelease(framesetter);

returndictionary;

}