无法将类型的价值“[字符串：AnyObject] ?.类型”（又名“可选<词典<字符串，AnyObject >>型）预期的参数类型

Question

收到此错误上size = text.boundingRectWithSize

不能转换键入'[String：AnyObject] ?.类型'（又名 'Optional> .Type）与预期参数 type'[String：AnyObject]？'

func heightOfString(text: NSString!, width: CGFloat, font: UIFont) -> CGFloat{ 
    var ch:CGFloat! 
    var size:CGSize = CGSizeMake(width, CGFloat.max) 

    var tdic:NSDictionary = NSDictionary(objects: [font, NSFontAttributeName], forKeys: []) 
    size = text.boundingRectWithSize(size, options: NSStringDrawingOptions.UsesFontLeading , attributes: [String : AnyObject]?, context: nil).size 
    ch = size.height 
    return ch 

} 

Answer 1

如果你需要传递一个空字典的属性，使用[:]

size = text.boundingRectWithSize(size, options: NSStringDrawingOptions.UsesFontLeading , attributes: [:], context: nil).size