Question

我有一个带有项目的表视图。如果我点击某个项目，则会显示其详细视图。现在每个项目都有两个表示有意义状态的枚举状态。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个组合。对于每个组合，我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字＆＃34;？开关结构非常大。有更简洁的解决方案吗？

Answer 1

我们可以使用2的幂来给出一些独特的密钥。我们可以随意复合这些唯一键，结果仍然是唯一的。 History of the Binary System

每个数字都有唯一的二进制表示这一事实告诉我们每个数字都可以用一种独特的方式表示为由于L.欧拉，我希望提供一份独立的证据（1707-1783）[Dunham，p 166]后者的结果。

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);

在详细视图上改变文本

1 个答案: