IOS7.0 sizeWithFont:constrainedToSize:lineBreakMode:方法 iOS7 Deprecated

之前使用了NSString类的sizeWithFont:constrainedToSize:lineBreakMode:方法，但是该方法已经被iOS7 Deprecated了，而iOS7新出了一个boudingRectWithSize:options:attributes:context方法来代替。

而具体怎么使用呢，尤其那个attribute

<pre name="code" class="objc">//NSDictionary *attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:13]};
//设置段落模式
NSMutableParagraphStyle *paragraph = [[NSMutableParagraphStyle alloc] init];
paragraph.alignment = NSLineBreakByWordWrapping;
NSDictionary *attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:13], NSParagraphStyleAttributeName: paragraph};

CGSize size = [@“相关NSString” boundingRectWithSize:CGSizeMake(100, 0) options: NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading attributes:attribute context:nil].size;