从NSMutableArray获取最大价值

Question

如何从NSMutableArray获取最大值。值存储为数组中的NSString，如下所示

for(int counter=0; counter<[datesArray count];counter++)
{
    glass = [NSString stringWithFormat:@"%f",[[dbhandler todayData:currentDate] floatValue]];
    [graphGlassesArray addObject:glass];
}

数组名称为graphGlassesArray。

Answer 1

您可以使用以下方法从数组中获取最大值：

NSNumber* max = [graphGlassesArray valueForKeyPath:@"max.self"];
float maxFloat = [max floatValue]

Answer 2

您还应该尝试使用键值编码（https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/KeyValueCoding/Articles/CollectionOperators.html）。要获得NSArray中的最大值，您可以[array valueForKeyPath:@"@max.attribute"]。请尝试查看此链接http://nshipster.com/kvc-collection-operators/。

Answer 3

float max = 0.f;
for(int counter=0; counter<[datesArray count];counter++)
{
    glass = [NSString stringWithFormat:@"%f",[[dbhandler todayData:currentDate] floatValue]];
    [graphGlassesArray addObject:glass];
    if(max < [[dbhandler todayData:currentDate] floatValue]) {
        max = [[dbhandler todayData:currentDate] floatValue];
    }
}

试试这个

Answer 4

尝试排序可变数组

NSSortDescriptor *desc = [[NSSortDescriptor alloc] initWithKey:nil ascending:NO selector:@selector(localizedCompare:)]; 
NSString *maxValue = [[graphGlassesArray sortedArrayUsingDescriptors:[NSArray arrayWithObject:desc]] objectAtIndex:0];
[desc release];