IOS学习 对应IOS8计算文字范围

知识补充:MAXFLOAT和CGFLOAT_MAX

MAXFLOAT是最大的float

CGFLOAT_MAX32位上最大的float  64位上最大的double

IOS8计算文字CGSize:

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStylealloc]init];

        paragraphStyle.lineBreakMode =NSLineBreakByCharWrapping;

        CGSize rect = [str boundingRectWithSize:sizeoptions:NSStringDrawingUsesLineFragmentOrigin |NSStringDrawingUsesFontLeading attributes:[NSDictionarydictionaryWithObjectsAndKeys:font,NSFontAttributeName,paragraphStyle,NSParagraphStyleAttributeName,nil] context:nil].size;

IOS7计算文字CGSize:

        CGSize rect = [strsizeWithFont:font constrainedToSize:sizelineBreakMode:NSLineBreakByCharWrapping];

- (CGSize)drawAtPoint:(CGPoint)point withFont:(UIFont *)fontNS_DEPRECATED_IOS(2_0,7_0, "Use -drawAtPoint:withAttributes:");

- (CGSize)drawAtPoint:(CGPoint)point forWidth:(CGFloat)width withFont:(UIFont *)font lineBreakMode:(NSLineBreakMode)lineBreakMode NS_DEPRECATED_IOS(2_0,7_0, "Use -drawInRect:withAttributes:");

drawAtPoint中的CGPoint组成drawInRect的CGRect，forWidth为size.weight,通常高就用CGFLOAT_MAX32

具体Attributes的使用请看上一篇文章