xcode 强制洗牌 NSMutableArray
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Force Shuffle NSMutableArray
提问by Alex G
I have a NSMutableArray called putNumberUsed. It contains the following objects @"blah1,@"blah2",@"blah3",@"blah4". I want to shuffle these objects randomly so for example if I chose:
我有一个名为 putNumberUsed 的 NSMutableArray。它包含以下对象@"blah1,@"blah2",@"blah3",@"blah4"。我想随机调整这些对象，例如，如果我选择：
[putNumberUsed objectAtIndex:0]
it would give me anything but "blah1". How would I go about doing this? The following is the code I used thus far:
它会给我除了 "blah1" 之外的任何东西。我该怎么做呢？以下是我迄今为止使用的代码：
NSMutableArray *putNumbersUsed = [[NSMutableArray alloc] arrayWithObjects:@"blah1",@"blah2",@"blah3",@"blah4",nil];
回答by Rajesh
I think, You can write a loop for that. Please check the following code,
我认为，您可以为此编写一个循环。请检查以下代码，
for (int i = 0; i < putNumberUsed.count; i++) {
int randomInt1 = arc4random() % [putNumberUsed count];
int randomInt2 = arc4random() % [putNumberUsed count];
[putNumberUsed exchangeObjectAtIndex:randomInt1 withObjectAtIndex:randomInt2];
}
I this this may be useful to you.
我这可能对你有用。
回答by Mukesh
From iOS 10.x++ new concept of shuffle arrayis given by Apple,
从 iOS 10.x++ 开始，Apple 给出了shuffle 数组的新概念，
You need to import the framework :
您需要导入框架：
ObjeC
对象C
#import <GameplayKit/GameplayKit.h>
NSArray *shuffledArray = [yourArray shuffledArray];
Swift
迅速
import GameplayKit
let shuffledArray = yourArray.shuffled()
回答by C?ur
Here is a shuffling solution with all positions forced to change when count > 1.
这是一个改组解决方案，当计数 > 1 时，所有位置都被迫改变。
Add a category like NSMutableArray+Shuffle.m:
添加类似 NSMutableArray+Shuffle.m 的类别：
@implementation NSMutableArray (Shuffle)
// Fisher-Yates shuffle variation with all positions forced to change
- (void)unstableShuffle
{
for (NSInteger i = self.count - 1; i > 0; i--)
// note: we use u_int32_t because `arc4random_uniform` doesn't support int64
[self exchangeObjectAtIndex:i withObjectAtIndex:arc4random_uniform((u_int32_t)i)];
}
@end
Then you can shuffle like:
然后你可以像这样洗牌：
[putNumbersUsed unstableShuffle];
This solution:
这个解决方案：
- has no modulo bias
- has no naive bias
- has no sorting bias
A Swift 3.2 and Swift 4 equivalent is:
Swift 3.2 和 Swift 4 等效项是：
extension Array {
mutating func unstableShuffle() {
for i in stride(from: count - 1, to: 0, by: -1) {
swapAt(i, Int(arc4random_uniform(UInt32(i))))
}
}
}
A Swift 3.0 and 3.1 equivalent is:
Swift 3.0 和 3.1 等效项是：
extension Array {
mutating func unstableShuffle() {
for i in stride(from: count - 1, to: 0, by: -1) {
swap(&self[i], &self[Int(arc4random_uniform(UInt32(i)))])
}
}
}
回答by Rajesh
You can shuffle the object by using the following line of code,
您可以使用以下代码行来洗牌对象，
[putNumbersUsed exchangeObjectAtIndex:3 withObjectAtIndex:0];
I think this may useful to you.
我认为这可能对你有用。
回答by janusfidel
generate a random number for index
为索引生成一个随机数
int randomInt = arc4random() % [putNumberUsed count];
[putNumberUsed objectAtIndex:randomInt];
回答by Fabio Poloni
Use this:
用这个：
for (int i = 0; i < [putNumberUsed count]; i++) {
int random = arc4random() % [putNumberUsed count];
[putNumbersUsed exchangeObjectAtIndex:random withObjectAtIndex:i];
}
