NSDictionary-需要检查 dictionary 是否包含键-值对

我只是想问你一些事情。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，我需要检查以下内容

[ xyz 是否包含键“ b”值? ？

问题是怎么做到的？

另一个问题是如何计算总键值对？

比如说 NSInteger mCount=[xyz keyCounts];

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最佳答案

Just ask it for the objectForKey:@"b". If it returns nil, no object is set at that key.

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 NSDictionary class reference ([1] [2]).

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With literal syntax you can check as follows

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);