使用NSPredicate比较两个数组 [英] Comparing two arrays with NSPredicate

问题描述

我有两个数组，一个表示全尺寸图像的列表，另一个表示图像的缩略图。有一种方法，使用NSPredicate，检查一个全尺寸的图像是否有缩略图？

拇指被称为img {number} _thumb.jpg，

使用数组，字符串和循环：

  NSArray * thumbs = @ [@img1_thumb.jpg，@img2_thumb.jpg，@img3_thumb.jpg ，@img4_thumb.jpg，@img5_thumb.jpg，]; 
 NSArray * images = @ [@img1，@img2，@img3，@img41，@img5]; 
 
 BOOL isSame = YES; 
 for（NSString * name in images）{
 if（！[thumbs containsObject：[NSString stringWithFormat：@％@ _ thumb.jpg，name]]）{
 isSame = NO; 
 NSLog（@％@没有缩略图，name）; 
 break; //如果第一个未找到不够好删除此打破
} 
} 
 NSLog（@％@，isSame？@所有拇指有图像：@所有拇指没有图像）; 
  

---

使用NSPredicate：

  for（NSString * image in images）{
 NSPredicate * predicate = [NSPredicate predicateWithFormat：@SELF like [c]％@ NSString stringWithFormat：@％@ _ thumb.jpg，image]]; 
 NSArray * filtered = [thumbs filteredArrayUsingPredicate：predicate]; 
 if（filtered.count == 0）{
 NSLog（@％@ not found，image）; 
} 
} 
  

I've two array, one represents a list of full-size images and the other one represents the images' thumbnail. There is a way, using NSPredicate, to check if a full-size image has a thumbnail?

The thumb is called img{number}_thumb.jpg and the full-size image is called img{number}.jpg.

解决方案

Using Arrays, strings and loop :

NSArray *thumbs=@[@"img1_thumb.jpg",@"img2_thumb.jpg",@"img3_thumb.jpg",@"img4_thumb.jpg",@"img5_thumb.jpg",];
NSArray *images=@[@"img1",@"img2",@"img3",@"img41",@"img5"];

BOOL isSame=YES;
for (NSString *name in images) {
    if (![thumbs containsObject:[NSString stringWithFormat:@"%@_thumb.jpg",name]]) {
        isSame=NO;
        NSLog(@"%@ doesn't has thumb image",name);
        break; //if first not found is not good enough remove this break
    }
}
NSLog(@"%@",isSame?@"All thumb has image":@"All thumb does not have image");

---

Using NSPredicate:

for (NSString *image in images) {
    NSPredicate *predicate=[NSPredicate predicateWithFormat:@"SELF like [c]%@",[NSString stringWithFormat:@"%@_thumb.jpg",image]];
    NSArray *filtered=[thumbs filteredArrayUsingPredicate:predicate];
    if (filtered.count==0) {
        NSLog(@"%@ not found",image);
    }
}

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