The height of the weex <text> component is not accurate? - ios

Question

The current WeexSDK version 0.18.0，I use show similar effect on the simulator and the real machine and the text can't be fully displayed as shown below.
Also I've added the script to show how to calculate the height of the text component in source code is done. suggestSize.heightis always the height I want, but this code is only executed under iOS10. The value of totalHeight is always worse when I have more text lines than iOS10. How do I solve this?
The effect is as follows：
The source code:
- (CGSize)calculateTextHeightWithWidth:(CGFloat)aWidth
{
CGFloat totalHeight = 0;
CGSize suggestSize = CGSizeZero;
NSAttributedString * attributedStringCpy = [self ctAttributedString];
if (!attributedStringCpy) {
return CGSizeZero;
}
if (isnan(aWidth)) {
aWidth = CGFLOAT_MAX;
}
aWidth = [attributedStringCpy boundingRectWithSize:CGSizeMake(aWidth, CGFLOAT_MAX) options:NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading context:nil].size.width;
/* Must get ceil of aWidth. Or core text may not return correct bounds.
Maybe aWidth without ceiling triggered some critical conditions. */
aWidth = ceil(aWidth);
CTFramesetterRef ctframesetterRef = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef)(attributedStringCpy));
suggestSize = CTFramesetterSuggestFrameSizeWithConstraints(ctframesetterRef, CFRangeMake(0, 0), NULL, CGSizeMake(aWidth, MAXFLOAT), NULL);
if (_lines == 0) {
// If not line limit use suggestSize directly.
CFRelease(ctframesetterRef);
return CGSizeMake(aWidth, suggestSize.height);
}
CGMutablePathRef path = NULL;
path = CGPathCreateMutable();
// sufficient height to draw text
CGPathAddRect(path, NULL, CGRectMake(0, 0, aWidth, suggestSize.height * 10));
CTFrameRef frameRef = NULL;
frameRef = CTFramesetterCreateFrame(ctframesetterRef, CFRangeMake(0, attributedStringCpy.length), path, NULL);
CGPathRelease(path);
CFRelease(ctframesetterRef);
if (NULL == frameRef) {
//try to protect unexpected crash.
return suggestSize;
}
CFArrayRef lines = CTFrameGetLines(frameRef);
CFIndex lineCount = CFArrayGetCount(lines);
CGFloat ascent = 0;
CGFloat descent = 0;
CGFloat leading = 0;
// height = ascent + descent + lineCount*leading
// ignore linespaing
NSUInteger actualLineCount = 0;
for (CFIndex lineIndex = 0; (!_lines|| lineIndex < _lines) && lineIndex < lineCount; lineIndex ++)
{
CTLineRef lineRef = NULL;
lineRef = (CTLineRef)CFArrayGetValueAtIndex(lines, lineIndex);
CTLineGetTypographicBounds(lineRef, &ascent, &descent, &leading);
totalHeight += ascent + descent;
actualLineCount ++;
}
totalHeight = totalHeight + actualLineCount * leading;
CFRelease(frameRef);
if (WX_SYS_VERSION_LESS_THAN(#"10.0")) {
// there is something wrong with coreText drawing text height, trying to fix this with more efficent way.
if(actualLineCount && actualLineCount < lineCount) {
suggestSize.height = suggestSize.height * actualLineCount / lineCount;
}
return CGSizeMake(aWidth, suggestSize.height);
}
return CGSizeMake(aWidth, totalHeight);
}