转载：@devchena 的swift方法转成Object-C方法：http://www.jianshu.com/p/0dd6141c46db （swift篇）
计算文本高度
+ (CGFloat)heightText:(NSString *)text inWidth:(CGFloat)width font:(UIFont *)font
{
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:font, NSFontAttributeName, nil];
CGRect rect = [text boundingRectWithSize:CGSizeMake(width, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:dict context:nil];
return ceilf(rect.size.height);
}
设置行间距时计算文本高度
+ (CGFloat)heightText:(NSString *)text inWidth:(CGFloat)width font:(UIFont *)font lineSpacing:(CGFloat)lineSpacing
{
NSMutableDictionary *mDictionary = [[NSMutableDictionary alloc] init];
[mDictionary setObject:font forKey:NSFontAttributeName];
[mDictionary setObject:[NSNumber numberWithInt:0] forKey:NSBaselineOffsetAttributeName];
if (lineSpacing) {
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
paragraphStyle.lineSpacing = lineSpacing;
[mDictionary setObject:paragraphStyle forKey:NSParagraphStyleAttributeName];
}
CGRect rect = [text boundingRectWithSize:CGSizeMake(width, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:mDictionary context:nil];
CGFloat spacing = rect.size.height - font.lineHeight;
if (spacing <= lineSpacing && spacing > 0) {
return ceilf(font.lineHeight);
}
return ceilf(rect.size.height);
}
设置间距并限制显示行数时计算高度
+ (CGFloat)heightText:(NSString *)text inWidth:(CGFloat)width font:(UIFont *)font lineSpacing:(CGFloat)lineSpacing lines:(int)lines
{
if (lines < 0) {
return 0;
}
CGFloat height = [self heightText:text inWidth:width font:font lineSpacing:lineSpacing];
if (lines == 0) {
return ceil(height);
}
CGFloat maximumHeight = font.lineHeight * lines + MAX(lineSpacing * (lines - 1), 10);
if (height >= maximumHeight) {
return ceilf(maximumHeight);
}
return ceilf(height);
}
