How to get a object from array for a particular value

Question

In swift i am using this code to get particular object for a particular value

if let layer = self.layers.first(where: {$0.id == id}) { }

I want to use this same in objective-c. How should i get a object from array of objects for particular value

I would recommend this lib github.com/google/functional-objc because Objective-C is missing real functional interfaces. — Sulthan
– Sulthan, Commented May 23, 2018 at 10:38

TheTiger · Accepted Answer · 2018-05-23 10:18:31Z

2

You can use NSPredicate in Objective-C to filter an array.

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"id == %@", id];
id layer = [[self.layers filteredArrayUsingPredicate:predicate] firstObject]

answered May 23, 2018 at 10:18

TheTiger

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battlmonstr · Accepted Answer · 2018-05-23 14:38:02Z

1

The predicateWithFormat solution is short, but not as type-safe as Swift.

To make it a bit more type-safe you could use indexOfObjectPassingTest.

Assuming you have:

@interface MyLayer
@property int layerID;
@end

NSArray<MyLayer *> *layers = @[...];
int layerIDToFind = 123;

You can write:

NSUInteger index = [layers indexOfObjectPassingTest:^BOOL(MyLayer *layer, NSUInteger idx, BOOL *stop) {
    return layer.layerID == layerIDToFind;
}];
if (index != NSNotFound) {
    MyLayer *layer = layers[index];
    // ... act on the layer ...
}

answered May 23, 2018 at 14:38

battlmonstr

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Comments

Jignesh Mayani · Accepted Answer · 2018-05-23 10:28:57Z

-1

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"id == %@", id];

NSArray *result = [self.layers filteredArrayUsingPredicate:predicate];

if result.count > 0
{
    id  layer = [result firstObject].id
}

edited May 23, 2018 at 10:28

answered May 23, 2018 at 10:26

Jignesh Mayani

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2 Comments

Yagnesh Dobariya Over a year ago

how you get .id value from array "result".

Jignesh Mayani Over a year ago

i have change that

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