objc写一个NSMutableArray不连续索引替换对象的方法
2024-08-20 22:56:11
NSMutableArray内置的方法-(void)replaceObjectsAtIndexes:(NSIndexSet*)set withObjects:(NSArray*)objs
只能替换一段连续索引内的对象,比如2 to 10之间的对象,如果我想要替换1,3,5索引位置的对象需要自己写代码。
在ruby中对于数组对象有一个values_at方法可以取得不连续索引的对象:
2.2.1 :048 > ary = %w[a b c d e f g]
=> ["a", "b", "c", "d", "e", "f", "g"]
2.2.1 :049 > ary.values_at(*[1,3,5])
=> ["b", "d", "f"]
如果是替换不连续索引的对象,稍微麻烦点:
2.2.1 :053 > idxes
=> [1, 3, 5]
2.2.1 :054 > objs
=> ["X", "X", "X"]
2.2.1 :055 > idxes.zip(objs)
=> [[1, "X"], [3, "X"], [5, "X"]]
2.2.1 :056 > idxes.zip(objs).each {|i,v|ary[i] = v}
=> [[1, "X"], [3, "X"], [5, "X"]]
2.2.1 :057 > ary
=> ["a", "X", "c", "X", "e", "X", "g"]
如果idxes数量小于objs则忽略多余的对象,反之如果idxes数量大于objs则用nil补足:
2.2.1 :062 > objs = %w[X X X]
=> ["X", "X", "X"]
2.2.1 :063 > idxes = [1,6]
=> [1, 6]
2.2.1 :064 > idxes.zip(objs).each {|i,v|ary[i] = v}
=> [[1, "X"], [6, "X"]]
2.2.1 :065 > ary
=> ["a", "X", "c", nil, "e", nil, "X"]
2.2.1 :059 > objs = []
=> []
2.2.1 :060 > idxes.zip(objs).each {|i,v|ary[i] = v}
=> [[1, nil], [3, nil], [5, nil]]
2.2.1 :061 > ary
=> ["a", nil, "c", nil, "e", nil, "g"]
下面写一个objc中类似的实现:
#import <Foundation/Foundation.h>
@interface NSMutableArray (HyRandReplace)
@end
@implementation NSMutableArray (HyRandReplace)
-(void)replaceObjectsAtIndexesRand:(NSArray*)idxes withObjects:(NSArray*)objs{
NSUInteger count_idxes = [idxes count];
//NSUInteger count_objs = [objs count];
for(NSUInteger i = 0;i < count_idxes;i++){
NSUInteger x = [idxes[i] intValue];
@try{
[self replaceObjectAtIndex:x withObject:objs[i]];
}
@catch(NSException *e){
NSLog(@"%@:%@",e.name,e.reason);
[self replaceObjectAtIndex:x withObject:[NSNull null]];
}
}
}
@end
int main(void){
@autoreleasepool{
NSArray *idxes = @[@1,@3,@5];
//NSArray *objs = @[@"LOVE",@"FOR"];
NSArray *objs =@[];
NSMutableArray *mary = [@[@"a",@"and",@"b",@"for",@"ever",@"..."]
mutableCopy];
NSLog(@"%@",mary);
[mary replaceObjectsAtIndexesRand:idxes withObjects:objs];
NSLog(@"%@",mary);
}
return 0;
}
当然ruby里也可以做类似的操作,why not?ruby比objc还要动态:
2.2.1 :066 > class Array
2.2.1 :067?> def replace_rand(idxes,objs)
2.2.1 :068?> idxes.zip(objs).each {|i,v|self[i] = v}
2.2.1 :069?> end
2.2.1 :070?> end
=> :replace_rand
2.2.1 :073 > ary
=> ["a", "b", "c", "d", "e", "f", "g"]
ary.replace_rand
2.2.1 :074 > ary.replace_rand(idxes,objs)
=> [[1, "X"], [6, "X"]]
2.2.1 :075 > ary
=> ["a", "X", "c", "d", "e", "f", "X"]
see!ruby扩展类要比objc简单的多,所以看swift的了 :)
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