NSString NSMutableString字符串 用一个字符替换其中的某个字符

不可变字符串 

//直接调用函数stringByReplacingOccurrencesOfString

 

NSString *time = [[timeString stringByReplacingOccurrencesOfString:@"T" withString:@" "] substringToIndex:[timeString lenth] - 1];

 

可变字符串

//直接调用函数replaceOccurrencesOfString

NSMutableString *string = [[NSMutableString alloc]initWithString:timeString] ;    

NSRange range = NSMakeRange(0, [string length]);    

[string replaceOccurrencesOfString:@"T" withString:@" " options:NSCaseInsensitiveSearch range:range];