iOS 16 计算文本尺寸崩溃
线上出现一个奇怪的崩溃, 堆栈信息比较少, 每天十几次, 发现是 iOS16 的新坑.
崩溃日志最后的堆栈是
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| CGSize size = [self.descriLabel.text calculateBoundingRectWithSize:CGSizeMake(sessionMaxWidth, CGFLOAT_MAX) font:[ComHelper regularSystemFontOfSize:14] paragraphStyle:paragraphStyle].size;
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我们 NSString 工具类计算尺寸出来崩溃, 计算用的 api 是boundingRectWithSize:options:attributes:context:context, 也是很常用的接口.
复现路径
一番定位后, 复现需要满足如下几个条件
- iOS 16 版本, 各个小版本均可
- 文本中含有
@" \n", 这个空格是 “NonBreakingSpace” 不间断空格, 空格后面接换行符
- attributes 中使用了 ParagraphStyle, 并且
alignment设置为了NSTextAlignmentJustified
- 换行符左边的文本足够长
什么是 “不间断空格”?
- 不间断空格 \u00a0, 主要用在office中, 让一个单词在结尾处不会换行显示, 快捷键ctrl+shift+space
- 半角空格(英文符号) \u0020, 代码中常用的
- 全角空格(中文符号) \u3000, 中文文章中使用
修复方案
这种特殊场景下换成正常的空格即可
测试代码
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| - (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
NSString *enterChar = @"\n";
NSString *normalSpace = @" "; // 普通空格 \u0020
NSString *nonBreakingSpace = @" "; // \u00a0
NSString *normalEmpty = @" \n"; // \u0020\n
NSString *errorEmpty = @" \n"; // \u00a0\n
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
[paragraphStyle setLineSpacing:8];
NSMutableParagraphStyle *paragraphStyle1 = [[NSMutableParagraphStyle alloc] init];
[paragraphStyle1 setLineSpacing:8];
paragraphStyle1.alignment = NSTextAlignmentJustified;
[self testA:enterChar count:30 left:@"abc" right:@"只" style:nil];
[self testA:normalSpace count:30 left:@"abc" right:@"只" style:nil];
[self testA:nonBreakingSpace count:30 left:@"abc" right:@"只" style:nil];
[self testA:normalEmpty count:30 left:@"abc" right:@"只" style:nil];
[self testA:errorEmpty count:30 left:@"abc" right:@"只" style:nil];
[self testA:enterChar count:30 left:@"abc" right:@"只" style:paragraphStyle];
[self testA:normalSpace count:30 left:@"abc" right:@"只" style:paragraphStyle];
[self testA:nonBreakingSpace count:30 left:@"abc" right:@"只" style:paragraphStyle];
[self testA:normalEmpty count:30 left:@"abc" right:@"只" style:paragraphStyle];
[self testA:errorEmpty count:30 left:@"abc" right:@"只" style:paragraphStyle];
[self testA:enterChar count:30 left:@"abc" right:@"只" style:paragraphStyle1];
[self testA:normalSpace count:30 left:@"abc" right:@"只" style:paragraphStyle1];
[self testA:nonBreakingSpace count:30 left:@"abc" right:@"只" style:paragraphStyle1];
[self testA:normalEmpty count:30 left:@"abc" right:@"只" style:paragraphStyle1];
// 只有这个会崩溃
[self testA:errorEmpty count:30 left:@"abc" right:@"只" style:paragraphStyle1];
NSLog(@"success");
}
- (void)testA:(NSString *)errorStr
count:(NSUInteger)count
left:(NSString *)left
right:(NSString *)right
style:(NSMutableParagraphStyle *)paragraphStyle
{
NSMutableString *leftStr = [[NSMutableString alloc] init];
NSMutableString *rightStr = [[NSMutableString alloc] init];
for (int i = 0; i < count; i++)
{
[leftStr appendString:left];
for (int j = 0; j < count; j++)
{
[rightStr appendString:right];
NSString *testStr = [NSString stringWithFormat:@"%@%@%@", leftStr, errorStr, rightStr];
NSDictionary *dic = @{
NSFontAttributeName: [UIFont systemFontOfSize:14 weight:UIFontWeightRegular],
};
if (paragraphStyle)
{
dic = @{
NSFontAttributeName: [UIFont systemFontOfSize:14 weight:UIFontWeightRegular],
NSParagraphStyleAttributeName: paragraphStyle
};
}
// left 比较长, 绘制导致换行, 超过了设置的宽度(300) 才会崩溃
CGRect rect = [testStr boundingRectWithSize:CGSizeMake(300, CGFLOAT_MAX)
options:NSStringDrawingUsesLineFragmentOrigin
attributes:dic
context:nil];
}
}
}
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