内容弃用的sizeWithFont：constrainedToSize到boundingRectWithSize：options：attributes：context：

Question

如何转换

 CGSize labelHeighSize = [text sizeWithFont: [UIFont systemFontOfSize:16] constrainedToSize:maximumSize lineBreakMode:NSLineBreakByTruncatingTail];

到

CGSize labelHeighSize = [text boundingRectWithSize:maximumSize options:  attributes:  context: 

Answer 1

首先是方法：

 - (CGRect)   boundingRectWithSize:(CGSize)size 
                           options:(NSStringDrawingOptions)options 
                        attributes:(NSDictionary *)attributes 
                           context:(NSStringDrawingContext *)context;

返回CGRect而不是CGSize，因此您需要使用CGRect。

修改 根据苹果文档，请参阅here，它说

  

如果NSStringDrawingUsesLineFragmentOrigin不是，则忽略此选项   也设定。此外，换行模式必须是   此选项的NSLineBreakByWordWrapping或NSLineBreakByCharWrapping   生效。换行模式可以在段落中指定   样式在图形的属性字典参数中传递   方法

以下是您可以使用的示例代码：

NSString *text = @"Some text to measure";
UIFont *labelFont = [UIFont systemFontOfSize:16];

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc]init];
//set the line break mode
paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping; 

NSDictionary *attrDict = [NSDictionary dictionaryWithObjectsAndKeys:labelFont,
                                       NSFontAttributeName,
                                       paragraphStyle,
                                       NSParagraphStyleAttributeName,
                                       nil];


//assume your maximumSize contains {255, MAXFLOAT}     
CGRect lblRect = [text boundingRectWithSize:(CGSize){225, MAXFLOAT} 
                                    options:NSStringDrawingUsesLineFragmentOrigin
                                 attributes:attrDict 
                                    context:nil];
CGSize labelHeighSize = lblRect.size;