iCarousel滚动不流畅

Question

我正在使用iCarousel滚动标签。在Simulator上一切正常，但在iPad/iPhone上滚动并不流畅和快速

以下是代码。

CitiesListView.h

#import <UIKit/UIKit.h>
#import "iCarousel.h"

@interface CitiesListView : UIView <iCarouselDataSource, iCarouselDelegate>

@property (nonatomic, retain)  iCarousel *carousel;


@end

CitiesListView.m

#import "CitiesListView.h"

@interface CitiesListView ()


@property (nonatomic, retain) NSMutableArray *items;

@end

@implementation CitiesListView

@synthesize carousel;
@synthesize items;

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self setUp];
    }
    return self;
}

- (void)setUp
{
    carousel = [[iCarousel alloc]initWithFrame:CGRectMake(0, 0, 300, 200)];
       items = [NSMutableArray arrayWithObjects:@"city1", @"city2", @"city3", @"city4", @"city5", @"city6", nil];
    [self addSubview:carousel];
    carousel.delegate = self;
    carousel.dataSource = self;
    carousel.type = iCarouselTypeRotary;

}

- (id)initWithCoder:(NSCoder *)aDecoder
{
    if ((self = [super initWithCoder:aDecoder]))
    {
        [self setUp];
    }
    return self;
}

#pragma mark iCarousel methods

- (NSUInteger)numberOfItemsInCarousel:(iCarousel *)carousel
{
    return [items count];
}

- (UIView *)carousel:(iCarousel *)carousel viewForItemAtIndex:(NSUInteger)index reusingView:(UIView *)view
{
    UILabel *label = nil;

    //create new view if no view is available for recycling
    if (view == nil)
    {
        view = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 200.0f, 200.0f)];
        ((UIImageView *)view).image = [UIImage imageNamed:@"labelBackground.png"];
        view.contentMode = UIViewContentModeCenter;
        label = [[UILabel alloc] initWithFrame:view.bounds];
        label.backgroundColor = [UIColor clearColor];
        label.textAlignment = UITextAlignmentCenter;
        label.font = [label.font fontWithSize:26];
        label.tag = 1;
        [view addSubview:label];
    } else {
        //get a reference to the label in the recycled view
        label = (UILabel *)[view viewWithTag:1];
    }

    //set item label
    //remember to always set any properties of your carousel item
    //views outside of the `if (view == nil) {...}` check otherwise
    //you'll get weird issues with carousel item content appearing
    //in the wrong place in the carousel
    label.text = [items objectAtIndex:index];
    return view;
}

- (NSUInteger)numberOfPlaceholdersInCarousel:(iCarousel *)carousel
{
    //note: placeholder views are only displayed on some carousels if wrapping is disabled
    return 2;
}

- (UIView *)carousel:(iCarousel *)carousel placeholderViewAtIndex:(NSUInteger)index reusingView:(UIView *)view
{
    UILabel *label = nil;

    //create new view if no view is available for recycling
    if (view == nil)
    {
        //don't do anything specific to the index within
        //this `if (view == nil) {...}` statement because the view will be
        //recycled and used with other index values later
        view = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 200.0f, 200.0f)];
        ((UIImageView *)view).image = [UIImage imageNamed:@"labelBackground.png"];
        view.contentMode = UIViewContentModeCenter;

        label = [[UILabel alloc] initWithFrame:view.bounds];
        label.backgroundColor = [UIColor clearColor];
        label.textAlignment = UITextAlignmentCenter;
        label.font = [label.font fontWithSize:50.0f];
        label.tag = 1;
        [view addSubview:label];
    } else {
        //get a reference to the label in the recycled view
        label = (UILabel *)[view viewWithTag:1];
    }

    //set item label
    //remember to always set any properties of your carousel item
    //views outside of the `if (view == nil) {...}` check otherwise
    //you'll get weird issues with carousel item content appearing
    //in the wrong place in the carousel
    label.text = (index == 0)? @"[": @"]";

    return view;
}

- (CATransform3D)carousel:(iCarousel *)_carousel itemTransformForOffset:(CGFloat)offset baseTransform:(CATransform3D)transform
{
    //implement 'flip3D' style carousel
    transform = CATransform3DRotate(transform, M_PI / 8.0f, 0.0f, 1.0f, 0.0f);
    return CATransform3DTranslate(transform, 0.0f, 0.0f, offset * carousel.itemWidth);
}

- (CGFloat)carousel:(iCarousel *)_carousel valueForOption:(iCarouselOption)option withDefault:(CGFloat)value
{
    //customize carousel display
    switch (option)
    {
        case iCarouselOptionSpacing:
        {
            //add a bit of spacing between the item views
            return value * 1.05f;
        }
        case iCarouselOptionFadeMax:
        {
            if (carousel.type == iCarouselTypeCustom)
            {
                //set opacity based on distance from camera
                return 0.0f;
            }
            return value;
        }
        default:
        {
            return value;
        }
    }
}

#pragma mark iCarousel taps

- (void)carousel:(iCarousel *)carousel didSelectItemAtIndex:(NSInteger)index
{
    NSNumber *item = [self.items objectAtIndex:index];
    NSLog(@"Tapped view number: %@", item);
}

@end

并在我的视图控制器alloc/initWithFrame CitiesListView中添加到self.view。

我做错了什么。我需要标签来滚动平滑的例子。

谢谢。

Answer 1

在您的setUp方法中，调用以下代码：

carousel.centerItemWhenSelected = YES;

也可以使用carousel.scrollSpeed (值: 0.0到1.0，默认值为1.0，表示最快)来更改滚动速度。

Answer 2

使用任何一种方法

索引(UIView *)carousel:(iCarousel *)carousel placeholderViewAtIndex：(NSUInteger)索引reusingView:(UIView *)查看

(或)

索引(UIView *)carousel:(iCarousel *)carousel viewForItemAtIndex：(NSUInteger)索引reusingView:(UIView *)查看

Answer 3

从根本上说，问题在于您试图一次将太多图像加载到内存中(视图数量x每个视图的动画帧数)。

您需要找到一种动态加载框架的方法。试试我的GLView库(https://github.com/nicklockwood/GLView)，它包含使用可以实时加载的PVR图像播放动画的说明。GLView库包含一个GLImageView类，它的工作方式与UIImageView类似，但是让我们指定一个要播放的图像文件名数组，而不必预先加载所有图像。