在iOS 7中替换已弃用的sizeWithFont:

Question

在iOS 7中,sizeWithFont:现已弃用.我现在如何将UIFont对象传递给替换方法sizeWithAttributes:？

Answer 1

使用sizeWithAttributes:相反,现在需要的NSDictionary.使用密钥UITextAttributeFont和您的字体对象传递对,如下所示:

CGSize size = [string sizeWithAttributes:
    @{NSFontAttributeName: [UIFont systemFontOfSize:17.0f]}];

// Values are fractional -- you should take the ceilf to get equivalent values
CGSize adjustedSize = CGSizeMake(ceilf(size.width), ceilf(size.height));

Answer 2

我相信该函数已被弃用,因为该系列NSString+UIKit函数(sizewithFont:...等)基于UIStringDrawing库,这不是线程安全的.如果您尝试不在主线程上运行它们(就像任何其他UIKit功能一样),您将获得不可预测的行为.特别是,如果您同时在多个线程上运行该函数,它可能会使您的应用程序崩溃.这就是为什么在iOS 6中他们引入了一种boundingRectWithSize:...方法NSAttributedString.它建立在NSStringDrawing库之上,并且是线程安全的.

如果查看新NSString boundingRectWithSize:...函数,它会以与a相同的方式请求属性数组NSAttributeString.如果我不得不猜测,NSStringiOS 7中的这个新功能仅仅是NSAttributeStringiOS 6中的功能包装.

关于这一点,如果你只支持iOS 6的和iOS 7,那么我肯定会所有的改变NSString sizeWithFont:...的NSAttributeString boundingRectWithSize.如果您碰巧有一个奇怪的多线程角落案例,它会为您省去很多麻烦!这是我转换的方式NSString sizeWithFont:constrainedToSize::

过去是什么:

NSString *text = ...;
CGFloat width = ...;
UIFont *font = ...;
CGSize size = [text sizeWithFont:font 
               constrainedToSize:(CGSize){width, CGFLOAT_MAX}];

可以替换为:

NSString *text = ...;
CGFloat width = ...;
UIFont *font = ...;
NSAttributedString *attributedText =
    [[NSAttributedString alloc] initWithString:text 
                                    attributes:@{NSFontAttributeName: font}];
CGRect rect = [attributedText boundingRectWithSize:(CGSize){width, CGFLOAT_MAX}
                                           options:NSStringDrawingUsesLineFragmentOrigin
                                           context:nil];
CGSize size = rect.size;

请注意文档提到:

在iOS 7及更高版本中,此方法返回小数大小(在返回的大小组件中CGRect); 要使用返回的大小来调整视图大小,必须使用ceil函数将其值提升到最接近的更高整数.

因此,要拉出用于调整视图大小的计算高度或宽度,我会使用:

CGFloat height = ceilf(size.height);
CGFloat width  = ceilf(size.width);

Answer 3

正如您sizeWithFont在Apple Developer网站上看到的那样,它已被弃用,因此我们需要使用它sizeWithAttributes.

#define SYSTEM_VERSION_LESS_THAN(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)

NSString *text = @"Hello iOS 7.0";
if (SYSTEM_VERSION_LESS_THAN(@"7.0")) {
    // code here for iOS 5.0,6.0 and so on
    CGSize fontSize = [text sizeWithFont:[UIFont fontWithName:@"Helvetica" 
                                                         size:12]];
} else {
    // code here for iOS 7.0
   CGSize fontSize = [text sizeWithAttributes: 
                            @{NSFontAttributeName: 
                              [UIFont fontWithName:@"Helvetica" size:12]}];
}

Answer 4

我创建了一个类别来处理这个问题,这里是:

#import "NSString+StringSizeWithFont.h"

@implementation NSString (StringSizeWithFont)

- (CGSize) sizeWithMyFont:(UIFont *)fontToUse
{
    if ([self respondsToSelector:@selector(sizeWithAttributes:)])
    {
        NSDictionary* attribs = @{NSFontAttributeName:fontToUse};
        return ([self sizeWithAttributes:attribs]);
    }
    return ([self sizeWithFont:fontToUse]);
}

这样,您只需要查找/替换sizeWithFont:用sizeWithMyFont:,你是好去.

Answer 5

在iOS7中,我需要逻辑来返回tableview的正确高度:heightForRowAtIndexPath方法,但sizeWithAttributes总是返回相同的高度而不管字符串长度,因为它不知道它将被放入固定宽度的表格单元格中.我发现这对我很有用,并考虑到表格单元格的宽度来计算正确的高度!这是基于T先生的上述答案.

NSString *text = @"The text that I want to wrap in a table cell."

CGFloat width = tableView.frame.size.width - 15 - 30 - 15;  //tableView width - left border width - accessory indicator - right border width
UIFont *font = [UIFont systemFontOfSize:17];
NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:text attributes:@{NSFontAttributeName: font}];
CGRect rect = [attributedText boundingRectWithSize:(CGSize){width, CGFLOAT_MAX}
                                           options:NSStringDrawingUsesLineFragmentOrigin
                                           context:nil];
CGSize size = rect.size;
size.height = ceilf(size.height);
size.width  = ceilf(size.width);
return size.height + 15;  //Add a little more padding for big thumbs and the detailText label

Answer 6

使用动态高度的多行标签可能需要其他信息才能正确设置大小.您可以将sizeWithAttributes与UIFont和NSParagraphStyle一起使用来指定字体和换行模式.

您将定义段落样式并使用如下的NSDictionary:

// set paragraph style
NSMutableParagraphStyle *style = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
[style setLineBreakMode:NSLineBreakByWordWrapping];
// make dictionary of attributes with paragraph style
NSDictionary *sizeAttributes        = @{NSFontAttributeName:myLabel.font, NSParagraphStyleAttributeName: style};
// get the CGSize
CGSize adjustedSize = CGSizeMake(label.frame.size.width, CGFLOAT_MAX);

// alternatively you can also get a CGRect to determine height
CGRect rect = [myLabel.text boundingRectWithSize:adjustedSize
                                                         options:NSStringDrawingUsesLineFragmentOrigin
                                                      attributes:sizeAttributes
                                                         context:nil];

如果您正在寻找高度,可以使用CGSize'contatedSize'或CGRect作为rect.size.height属性.

有关NSParagraphStyle的更多信息,请访问:https://developer.apple.com/library/mac/documentation/cocoa/reference/applicationkit/classes/NSParagraphStyle_Class/Reference/Reference.html

Answer 7

// max size constraint
CGSize maximumLabelSize = CGSizeMake(184, FLT_MAX)

// font
UIFont *font = [UIFont fontWithName:TRADE_GOTHIC_REGULAR size:20.0f];

// set paragraph style
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;

// dictionary of attributes
NSDictionary *attributes = @{NSFontAttributeName:font,
                             NSParagraphStyleAttributeName: paragraphStyle.copy};

CGRect textRect = [string boundingRectWithSize: maximumLabelSize
                                     options:NSStringDrawingUsesLineFragmentOrigin
                                  attributes:attributes
                                     context:nil];

CGSize expectedLabelSize = CGSizeMake(ceil(textRect.size.width), ceil(textRect.size.height));