Question

我正在尝试按字母顺序重新排列单词。例如，番茄会变得无法控制，或者堆积会变得很难。

我在C语言中找到了一些使用char数组的方法，但是我遇到了在NSString对象范围内工作的问题。

在NSString对象本身中有更简单的方法吗？

Answer 1

您可以将每个字符串的字符存储到NSArray个NSNumber个对象中，然后对其进行排序。看起来有点贵，所以我可能只会使用qsort()。

这里它是作为Objective-C类别（未经测试）提供的：

的NSString + SortExtension.h：

#import <Foundation/Foundation.h>

@interface NSString (SortExtension)
- (NSString *)sorted;
@end

的NSString + SortExtension.m：

#import "NSString+SortExtension.h"

@implementation NSString (SortExtension)

- (NSString *)sorted
{
    // init
    NSUInteger length = [self length];
    unichar *chars = (unichar *)malloc(sizeof(unichar) * length);

    // extract
    [self getCharacters:chars range:NSMakeRange(0, length)];

    // sort (for western alphabets only)
    qsort_b(chars, length, sizeof(unichar), ^(const void *l, const void *r) {
        unichar left = *(unichar *)l;
        unichar right = *(unichar *)r;
        return (int)(left - right);
    });

    // recreate
    NSString *sorted = [NSString stringWithCharacters:chars length:length];

    // clean-up
    free(chars);

    return sorted;
}

@end

Answer 2

我认为将字符串分隔为字符串数组（数组中的每个字符串只包含原始字符串中的一个字符）。然后排序数组就可以了。这不是很有效，但是当字符串不是很长时就足够了。我已经测试了代码。

NSString *str = @"stack";
NSMutableArray *charArray = [NSMutableArray arrayWithCapacity:str.length];
for (int i=0; i<str.length; ++i) {
    NSString *charStr = [str substringWithRange:NSMakeRange(i, 1)];
    [charArray addObject:charStr];
}

NSString *sortedStr = [[charArray sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)] componentsJoinedByString:@""];

Answer 3

// --------- Function To Make an Array from String
NSArray *makeArrayFromString(NSString *my_string) {
    NSMutableArray *array = [[NSMutableArray alloc] init];
    for (int i = 0; i < my_string.length; i ++) {
        [array addObject:[NSString stringWithFormat:@"%c", [my_string characterAtIndex:i]]];
    }
    return array;

}

// --------- Function To Sort Array
NSArray *sortArrayAlphabetically(NSArray *my_array) {
    my_array= [my_array sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
    return my_array;
}

// --------- Function Combine Array To Single String
NSString *combineArrayIntoString(NSArray *my_array) {
    NSString * combinedString = [[my_array valueForKey:@"description"] componentsJoinedByString:@""];
    return combinedString;
}




// Now you can call the functions as in below where string_to_arrange is your string
    NSArray *blowUpArray;
    blowUpArray = makeArrayFromString(string_to_arrange);
    blowUpArray = sortArrayAlphabetically(blowUpArray);
    NSString *arrayToString= combineArrayIntoString(blowUpArray);
    NSLog(@"arranged string = %@",arrayToString);

Answer 4

另一个使用NSMutableString和sortUsingComparator:的示例

NSMutableString *mutableString = [[NSMutableString alloc] initWithString:@"tomat"];
[mutableString appendString:@"o"];
NSLog(@"Orignal string: %@", mutableString);

NSMutableArray *charArray = [NSMutableArray array];
for (int i = 0; i < mutableString.length; ++i) {
    [charArray addObject:[NSNumber numberWithChar:[mutableString characterAtIndex:i]]];
}

[charArray sortUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {
    if ([obj1 charValue] < [obj2 charValue]) return NSOrderedAscending;
    return NSOrderedDescending;
}];

[mutableString setString:@""];
for (int i = 0; i < charArray.count; ++i) {
    [mutableString appendFormat:@"%c", [charArray[i] charValue]];
}

NSLog(@"Sorted string: %@", mutableString);

输出：

Orignal string: tomato
Sorted string: amoott

将NSString中的字符按字母顺序排序

4 个答案: