iOS：收到崩潰NSInvalidArgumentException NSConcreteMutableAttributedString addAttribute：value：range :: nil值

Question

這是發生錯誤的行。

[self addAttribute:(__bridge NSString*)kCTForegroundColorAttributeName value:(__bridge id)color.CGColor range:range]; 

這是完整的方法代碼。

-(void)setTextColor:(UIColor*)color range:(NSRange)range 
{ 
if (range.location != NSNotFound) { 
// kCTForegroundColorAttributeName 
[self removeAttribute:(__bridge NSString*)kCTForegroundColorAttributeName range:range]; // Work around for Apple leak 
[self addAttribute:(__bridge NSString*)kCTForegroundColorAttributeName value:(__bridge id)color.CGColor range:range]; 
    }} 

我試過如果沒有找到範圍，但仍然發生錯誤。任何提示或建議我做錯了什麼？

Answer 1

發生這種情況是因爲(__bridge id)color.CGColor是nil。
只要做到這樣，沒有任何多餘的轉換

[self addAttribute:NSForegroundColorAttributeName value:color range:range]; 

Answer 2

它在你的情況下，錯誤檢查，您需要：

if (range.location >= 0 && range.location < self.length){ 
    if (range.location + range.length >= self.length) 
     range.length = self.length - range.location; 

    [self removeAttribute:(__bridge NSString*)kCTForegroundColorAttributeName range:range]; // Work around for Apple leak 
    [self addAttribute:(__bridge NSString*)kCTForegroundColorAttributeName value:(__bridge id)color.CGColor range:range]; 
}