NSDictionary - 需要检查字典是否包含键值对

Question

我只需要问一下如下.假设我有一本字典.

NSMutableDictionary *xyz=[[NSMutableDictionary alloc] init];
[xyz setValue:@"sagar" forKey:@"s"];
[xyz setValue:@"amit" forKey:@"a"];
[xyz setValue:@"nirav" forKey:@"n"];
[xyz setValue:@"abhishek" forKey:@"a"];
[xyz setValue:@"xrox" forKey:@"x"];

现在,我需要检查如下

[xyz确实包含键"b"值？对还是不对？

问题是如何？

另一个问题是如何计算总键值对？

比如说 NSInteger mCount=[xyz keyCounts];

Answer 1

只要问它objectForKey:@"b".如果返回nil,则不在该键上设置对象.

if ([xyz objectForKey:@"b"]) {
    NSLog(@"There's an object set for key @\"b\"!");
} else {
    NSLog(@"No object set for key @\"b\"");
}

编辑:关于你编辑的第二个问题,它很简单NSUInteger mCount = [xyz count];.这两个答案都很好地记录在NSDictionary类引用中([1] [2]).