如何在 iOS 中检查 NSArray 为 null 或为空？
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How to check NSArray is null or empty in iOS?
提问by user403015
After a NSArray was alloc and init, if there is nothing added to the NSArray, how to check it is null or empty ?
一个 NSArray 被分配和初始化后，如果没有添加到 NSArray 中，如何检查它是 null 还是空？
Thanks.
谢谢。
回答by Chris Doble
if (array == nil || [array count] == 0) {
...
}
回答by Joshua Weinberg
NSArray has the count method, a common way to do it would be...
NSArray 有 count 方法，一种常用的方法是......
if (![self.myArray count])
{
}
That will check if the array has nothing in it, or if it is set to nil.
这将检查数组中是否没有任何内容，或者它是否设置为 nil。
回答by shabbirv
While we are all throwing out the same answers, I thought I would too.
虽然我们都抛出相同的答案，但我想我也会。
if ([array count] < 1) {
...
}
回答by Jason Cragun
and another
而另一个
if(!array || array.count==0)
回答by chaithraVeeresh
if([myarray count])It checks for both not empty and nil array.
if([myarray count])它检查非空和 nil 数组。
回答by infiniteLoop
use
用
(array.count ? array : nil)
It will return nil if array = nilas well as [array count] == 0
如果array = nil以及，它将返回 nil[array count] == 0
回答by soorej babu
if([arrayName count]==0)
{
//array is empty.
}
else
{
//array contains some elements.
}
回答by PgmFreek
Try this one
试试这个
if(array == [NSNull null] || [array count] == 0) {
}
回答by RandomGuy
You can use this :
你可以使用这个：
if (!anArray || [anArray count] == 0) {
/* Your code goes here */
}
回答by user313879
if (array == nil && [array count] == 0) {
...
}
I use this code because I am having trouble to my pickerview when its the array is empty
我使用此代码是因为当它的数组为空时我的选择器视图有问题
My code is
我的代码是
- (IBAction)btnSelect:(UIBarButtonItem *)sender { // 52
if (self.array != nil && [self.array count] != 0) {
NSString *select = [self.array objectAtIndex:[self.pickerView selectedRowInComponent:0]];
if ([self.pickListNumber isEqualToString:@"1"]) {
self.textFieldCategory.text = select;
self.textFieldSubCategory.text = @"";
} else if ([self.pickListNumber isEqualToString:@"2"]) {
self.textFieldSubCategory.text = select;
}
[self matchSubCategory:select];
} else {
UIAlertView *myAlertView = [[UIAlertView alloc] initWithTitle:@"Error"
message:@"You should pick Category first"
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles: nil];
[myAlertView show];
}
[self hidePickerViewContainer:self.viewCategory];
}
