ios NSDictionary - 需要检查字典是否包含键值对
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NSDictionary - Need to check whether dictionary contains key-value pair or not
提问by Sagar R. Kothari
I just need to ask something as follow. Suppose I am having a dictionary.
我只需要问一些如下。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"];
Now, I need to check as follows
现在，我需要检查如下
[xyz does contains key "b" value ?? pair or not?
[xyz 确实包含键“b”值？？配对与否？
Question is How?
问题是如何？
The other question is How to just count total key-value pair?
另一个问题是如何计算总键值对？
Say for example NSInteger mCount=[xyz keyCounts];
比如说 NSInteger mCount=[xyz keyCounts];
回答by Matt B.
Just ask it for the objectForKey:@"b". If it returns nil, no object is set at that key.
只需询问它的objectForKey:@"b". 如果它返回nil，则不会在该键上设置任何对象。
if ([xyz objectForKey:@"b"]) {
NSLog(@"There's an object set for key @\"b\"!");
} else {
NSLog(@"No object set for key @\"b\"");
}
Edit: As to your edited second question, it's simply NSUInteger mCount = [xyz count];. Both of these answers are documented well and easily found in the NSDictionaryclass reference ([1][2]).
编辑：至于您编辑的第二个问题，它只是NSUInteger mCount = [xyz count];. 这两个答案都有很好的记录，并且很容易在NSDictionary类参考 ( [1] [2]) 中找到。
回答by hariszaman
With literal syntax you can check as follows
使用文字语法，您可以检查如下
static const NSString* kKeyToCheck = @"yourKey"
if (xyz[kKeyToCheck])
NSLog(@"Key: %@, has Value: %@", kKeyToCheck, xyz[kKeyToCheck]);
else
NSLog(@"Key pair do not exits for key: %@", kKeyToCheck);
