iOS判断对象是否为空需考虑4种情况

给NSObject写个分类,方便用

@interface NSObject (additions)/** *  判断对象是否为空 *  PS：nil、NSNil、@""、@0 以上4种返回YES * *  @return YES 为空  NO 为实例对象 */+ (BOOL)dx_isNullOrNilWithObject:(id)object;@end

+ (BOOL)dx_isNullOrNilWithObject:(id)object;{    if (object == nil || [object isEqual:[NSNull null]]) {        return YES;    } else if ([object isKindOfClass:[NSString class]]) {        if ([object isEqualToString:@""]) {            return YES;        } else {            return NO;        }    } else if ([object isKindOfClass:[NSNumber class]]) {        if ([object isEqualToNumber:@0]) {            return YES;        } else {            return NO;        }    }    return NO;}