iOS 获取字符串在给定条件下的CGRect

这是NSString分类(NSString (NSExtendedStringDrawing))中的一个方法:

- (CGRect)boundingRectWithSize:(CGSize)size options:(NSStringDrawingOptions)options attributes:(nullableNSDictionary<NSString *,id> *)attributes context:(nullableNSStringDrawingContext *)context NS_AVAILABLE(10_11,7_0);

利用该方法可获取想得到的值.

  CGRect textRect = [_msgStr boundingRectWithSize:CGSizeMake(contentWidth, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading attributes:@{NSFontAttributeName : [UIFont systemFontOfSize:contentFont]} context:nil];