无法从 NSDictionary 获取值，而 NSDictionary 期望将 NSNumber 作为输出
我创建了一个如下所示的 NSDictionary ：
NSArray * alphabets = [NSArray arrayWithObjects:@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",@"i",@"j",@"k",@"l",@"m",@"n",@"o",@"p",@"q",@"r",@"s",@"t",@"u",@"v",@"w",@"x",@"y",@"z",nil];
alphaToNum = [NSMutableDictionary dictionary];
numToAlpha = [NSMutableDictionary dictionary];
for(NSString* character in alphabets)
{
[alphaToNum setObject:[NSNumber numberWithInteger:index] forKey:character];
[numToAlpha setObject:character forKey:[NSNumber numberWithInteger:index]];
index++;
}
现在我想访问如下所示的“numToAlpha”：
NSInteger code1;
NSNumber * nn = [numToAlpha objectForKey:code1];
并且我会收到错误，而在 objectforkey 手册中它明确表示 (id)objectforkey(id) 这意味着任何东西！
I have created a NSDictionary like following :
NSArray * alphabets = [NSArray arrayWithObjects:@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",@"i",@"j",@"k",@"l",@"m",@"n",@"o",@"p",@"q",@"r",@"s",@"t",@"u",@"v",@"w",@"x",@"y",@"z",nil];
alphaToNum = [NSMutableDictionary dictionary];
numToAlpha = [NSMutableDictionary dictionary];
for(NSString* character in alphabets)
{
[alphaToNum setObject:[NSNumber numberWithInteger:index] forKey:character];
[numToAlpha setObject:character forKey:[NSNumber numberWithInteger:index]];
index++;
}
now I want to access to "numToAlpha" like following :
NSInteger code1;
NSNumber * nn = [numToAlpha objectForKey:code1];
and I'll get error whereas in manual for objectforkey it clearly said (id)objectforkey(id) which means anything!
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NSInteger不是一个对象。id指任何对象类型。您需要使用[NSNumber numberWithInteger:code1]，就像您在代码示例中所做的那样。NSIntegeris not an object.idrefers to any object type. You need to use[NSNumber numberWithInteger:code1]as you are already doing in your code sample.