objective-c - 详细信息 View 上的不同文本

Question

我有一个包含项目的表格 View 。如果我单击一个项目，则会显示其详细 View 。现在每个项目都有两个枚举状态来表示有意义的状态。第一个枚举有 6 个不同的值，第二个枚举可以有 5 个不同的值。这给了我 30 种组合。对于每种组合，我都需要一个独特的文本。

在 cellForRowAtIndexPath 中提供正确的文本时:...我应该使用什么技术从该“网格”中选择正确的文本？开关结构相当大。有更简洁的解决方案吗？

Answer 1

我们可以使用 2 的幂来给出一些唯一的 key 。我们可以任意组合这些唯一的键，结果仍然是唯一的。 History of the Binary System

The fact that every number has a unique binary representation tells us that every number can be represented in a unique way as a sum of powers of 2. I wish to give an independent proof due to L. Euler (1707-1783) [Dunham, p 166] of the latter result.

对于代码:

typedef enum {
    FirstTypeOne = 1 << 0,
    FirstTypeTwo = 1 << 1,
    FirstTypeThree = 1 << 2,
    FirstTypeFour = 1 << 3,
    FirstTypeFive = 1 << 4,
    FirstTypeSix = 1 << 5
} FirstType;

typedef enum {
    SecondTypeSeven = 1 << 6,
    SecondTypeEight = 1 << 7,
    SecondTypeNine = 1 << 8,
    SecondTypeTen = 1 << 9,
    SecondTypeEleven = 1 << 10
} SecondType ;

const int FirstTypeCount = 6;
const int SecondTypeCount = 5;

// First create two array, each containing one of the corresponding enum value.
NSMutableArray *firstTypeArray = [NSMutableArray arrayWithCapacity:FirstTypeCount];
NSMutableArray *secondTypeArray = [NSMutableArray arrayWithCapacity:SecondTypeCount];

for (int i=0; i<FirstTypeCount; ++i) {
    [firstTypeArray addObject:[NSNumber numberWithInt:1<<i]];
}
for (int i=0; i<SecondTypeCount; ++i) {
    [secondTypeArray addObject:[NSNumber numberWithInt:1<<(i+FirstTypeCount)]];
}

// Then compute an array which contains the unique keys.
// Here if we use 
NSMutableArray *keysArray = [NSMutableArray arrayWithCapacity:FirstTypeCount * SecondTypeCount];
for (NSNumber *firstTypeKey in firstTypeArray) {
    for (NSNumber *secondTypeKey in secondTypeArray) {
        int uniqueKey = [firstTypeKey intValue] + [secondTypeKey intValue];
        [keysArray addObject:[NSNumber numberWithInt:uniqueKey]];
    }
}

// Keep the keys asending.
[keysArray sortUsingComparator:^(NSNumber *a, NSNumber *b){
    return [a compare:b];
}];

// Here you need to put your keys.
NSMutableArray *uniqueTextArray = [NSMutableArray arrayWithCapacity:keysArray.count];
for (int i=0; i<keysArray.count; ++i) {
    [uniqueTextArray addObject:[NSString stringWithFormat:@"%i text", i]];
}

// Dictionary with unique keys and unique text.
NSDictionary *textDic = [NSDictionary dictionaryWithObjects:uniqueTextArray forKeys:keysArray];

// Here you can use (FirstType + SecondType) as key.
// Bellow is two test demo.
NSNumber *key = [NSNumber numberWithInt:FirstTypeOne + SecondTypeSeven];
NSLog(@"text %@ for uniquekey %@", [textDic objectForKey:key], key);
key = [NSNumber numberWithInt:FirstTypeThree + SecondTypeNine];
NSLog(@"text %@ for uniquekey %@", [textDic objectForKey:key], key);