(Xcode IOS) - I'm trying to make a method which prefetches all the images and loads them into a tableView before scrolling (using SDWebImage). Anyways:
（Xcode IOS） - 我正在尝试制作一个预取所有图像的方法，并在滚动之前将它们加载到tableView中（使用SDWebImage）。无论如何：
I have an array of messages and each "message" is composed of a few different keys, PFFile, dateCreated, sender, etc...
我有一系列消息，每个“消息”由几个不同的密钥组成，PFFile，dateCreated，sender等...
What I need to do is take this array of @[ [PFFile], [dateCreated], [other info] ] -> @[ [PFFile] ]
我需要做的是取这个@ [[PFFile]，[dateCreated]，[其他信息]] - > @ [[PFFile]]
In other words, I need to make an array of just the PFFiles from the entire array. I was thinking of something like this (pseudocode)
换句话说，我需要从整个数组中创建一个只有PFFiles的数组。我在考虑这样的事情（伪代码）
self.urls = [self.messages objectsWithKey:@[PFFiles]];
self.urls = [self.messages objectsWithKey：@ [PFFiles]];
2 个解决方案
#1
1
It sounds like you are asking how to filter an array.
听起来你在问如何过滤数组。
self.urls = [self.messages objectsAtIndexes:[self.messages indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
return [obj isKindOfClass:[PFFile class]];
}]];
I like this syntax because you can use a block to return YES/NO if the object passes any sort of test you might want to write and it's a one-liner.
我喜欢这种语法，因为你可以使用一个块来返回YES / NO，如果对象通过了你可能要编写的任何类型的测试而且它是一行的。
#2
0
How about using combination of NSDictionary and NSArray ? You can put your array objects in a dictionary object.
如何使用NSDictionary和NSArray的组合？您可以将数组对象放在字典对象中。
#1
1
It sounds like you are asking how to filter an array.
听起来你在问如何过滤数组。
self.urls = [self.messages objectsAtIndexes:[self.messages indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
return [obj isKindOfClass:[PFFile class]];
}]];
I like this syntax because you can use a block to return YES/NO if the object passes any sort of test you might want to write and it's a one-liner.
我喜欢这种语法，因为你可以使用一个块来返回YES / NO，如果对象通过了你可能要编写的任何类型的测试而且它是一行的。
#2
0
How about using combination of NSDictionary and NSArray ? You can put your array objects in a dictionary object.
如何使用NSDictionary和NSArray的组合？您可以将数组对象放在字典对象中。