代码的安全性

不知道这样写会不会有问题 遇到的大神帮忙看看

字典赋值 如果赋的空值就会崩溃

1.字典取值是不会崩溃的 这样都不崩溃

NSDictionary *dicc = NULL;

NSString *str = dicc[@"2123"];

2. 预防取值崩溃

- (NSArray *)getSafeArray:(id)array
{
    if ([array isKindOfClass:[NSArray class]]) {
        return (NSArray *)array;
    } else {
        return [NSArray array];
    }
}
- (NSString *)getSafeString:(id)string
{
    if ([string isKindOfClass:[NSString class]])
        return (NSString *)string;
    else
        return @"";
}
- (NSDictionary *)getSafeDictory:(id)dic
{
    if ([dic isKindOfClass:[NSDictionary class]])
        return (NSDictionary *)dic;
    else
        return [NSDictionary dictionary];
}

3.判断是否是一个空的字符串 比如@"" @" "

- (BOOL) isBlankString:(NSString *)string
{
    if (string == nil || string == NULL) {
        return YES;
    }
    if ([string isKindOfClass:[NSNull class]]) {
        return YES;
    }
    if ([[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]] length]==0) {
        return YES;
    }
    return NO;
}