获取 NSString 高度

发布于 2024-11-28 04:47:39 字数 969 浏览 2 评论 0原文

我有一个 NSString，我想知道它的高度以创建合适的 UILabel。

现在做这个

NSString *string = @"this is an example"; 
CGSize size = [string sizeWithFont:[UIFont systemFontOfSize:10.0f] 
                          forWidth:353.0 
                     lineBreakMode:UILineBreakModeWordWrap];
float height = size.height;

高度是13.0。如果我使用这个字符串

NSString *string = @"this is an example this is an example this is an example 
                     this is an example this is an example this is an example 
                     this is an example this is an example this is an example 
                     this is an example this is an example this is an example 
                     this is an example this is an example this is an example 
                     this is an example ";

高度始终为 13.0（宽度为 353，这是不可能的）...我做错了什么？

ADD：

size.width;

工作正常...所以就像 lineBreakMode 不正确一样...但确实如此，不是吗？

原文

I have an NSString, and I want to know its height to create an appropriate UILabel.

Doing this

NSString *string = @"this is an example"; 
CGSize size = [string sizeWithFont:[UIFont systemFontOfSize:10.0f] 
                          forWidth:353.0 
                     lineBreakMode:UILineBreakModeWordWrap];
float height = size.height;

height is now 13.0.
If I use this string

NSString *string = @"this is an example this is an example this is an example 
                     this is an example this is an example this is an example 
                     this is an example this is an example this is an example 
                     this is an example this is an example this is an example 
                     this is an example this is an example this is an example 
                     this is an example ";

height is always 13.0 (and with 353 as width, that's impossible)... what am I doing wrong?

ADD:

size.width;

works fine... so it's like if the lineBreakMode is not correct... but it is, isn't it?

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深海夜未眠 2024-12-05 04:47:39

您所做的事情无法按预期工作的原因是因为

– sizeWithFont:forWidth:lineBreakMode:

is 用于“计算单行文本的指标”，而

-sizeWithFont:constrainedToSize:lineBreakMode:

is 用于“计算多行文本的指标”。来自文档：

计算单行文本的指标

– sizeWithFont：
– sizeWithFont:forWidth:lineBreakMode:
– sizeWithFont:minFontSize:actualFontSize:forWidth:lineBreakMode:

计算多行文本的指标

– sizeWithFont:constrainedToSize:
– sizeWithFont:constrainedToSize:lineBreakMode:

尝试使用 -sizeWithFont:constrainedToSize:lineBreakMode: 代替，例如，这是我通常所做的：

CGSize maximumLabelSize = CGSizeMake(353,9999);

CGSize expectedLabelSize = [string sizeWithFont:label.font                        
                              constrainedToSize:maximumLabelSize 
                                  lineBreakMode:label.lineBreakMode]; 

CGRect newFrame = label.frame;
newFrame.size.height = expectedLabelSize.height;
label.frame = newFrame;

The reason what you're doing doesn't work as you would expect is because

– sizeWithFont:forWidth:lineBreakMode:

is for "Computing Metrics for a Single Line of Text" whereas

-sizeWithFont:constrainedToSize:lineBreakMode:

is for "Computing Metrics for Multiple Lines of Text". From the documentation:

Computing Metrics for a Single Line of Text

– sizeWithFont:
– sizeWithFont:forWidth:lineBreakMode:
– sizeWithFont:minFontSize:actualFontSize:forWidth:lineBreakMode:

Computing Metrics for Multiple Lines of Text

– sizeWithFont:constrainedToSize:
– sizeWithFont:constrainedToSize:lineBreakMode:

Try using -sizeWithFont:constrainedToSize:lineBreakMode: instead, e.g. this is what I usually do:

CGSize maximumLabelSize = CGSizeMake(353,9999);

CGSize expectedLabelSize = [string sizeWithFont:label.font                        
                              constrainedToSize:maximumLabelSize 
                                  lineBreakMode:label.lineBreakMode]; 

CGRect newFrame = label.frame;
newFrame.size.height = expectedLabelSize.height;
label.frame = newFrame;

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