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UIScrollView的减速率可以修改吗?

cocoa-touch

Mike McMaster · 技术社区 · 17 年前

decelerationRate property 在OS 3.0中引入。

我有一个UIScrollView,我想改变它的减速率。为了清楚起见,我指的是当你在滚动视图上滑动手指时,当你抬起手指后,视图继续滚动(但逐渐变慢)。我想增加减速率,这样它就会比默认情况下更快地停止。

我见过一些应用程序的UIScrollViews似乎减速更快。在UIScrollView中似乎没有这个API,但我想知道是否有其他方法可以实现它。

5 回复 | 直到 14 年前

Anto Binish Kaspar 14 年前

你可以用 UIScrollView 的 decelerationRate 它不接受UIScrollViewDecelerationRateNormal或UIScrollViewDecelerationRateFast之外的任何值 . 请看下面的代码

NSLog(@"1. decelerationRate %f", scrollview.decelerationRate);

scrollview.decelerationRate = UIScrollViewDecelerationRateNormal;
NSLog(@"2. decelerationRate %f", scrollview.decelerationRate);

scrollview.decelerationRate = UIScrollViewDecelerationRateFast;
NSLog(@"3. decelerationRate %f", scrollview.decelerationRate);

scrollview.decelerationRate = 0.7;
NSLog(@"4. decelerationRate %f", scrollview.decelerationRate);

scrollview.decelerationRate = 0.995;
NSLog(@"5. decelerationRate %f", scrollview.decelerationRate);

上面的代码给出了以下输出,很明显我们不能使用自定义的减速率。

2012-01-03 11:59:41.164 testviewv2[10023:707] 1. decelerationRate 0.998000
2012-01-03 11:59:41.172 testviewv2[10023:707] 2. decelerationRate 0.998000
2012-01-03 11:59:41.173 testviewv2[10023:707] 3. decelerationRate 0.990000
2012-01-03 11:59:41.175 testviewv2[10023:707] 4. decelerationRate 0.990000
2012-01-03 11:59:41.176 testviewv2[10023:707] 5. decelerationRate 0.998000

shim 9 年前

scrollView.decelerationRate = UIScrollViewDecelerationRateFast;

mackross 13 年前

_decelerationFactor 允许我把价格改成别的 UIScrollViewDecelerationRateNormal 或 UIScrollViewDecelerationRateFast UIScrollView 把所有的东西都包在一个试块里

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
        @try {
            CGFloat decelerationRate = UIScrollViewDecelerationRateFast +(UIScrollViewDecelerationRateNormal - UIScrollViewDecelerationRateFast) * .52;
            [self setValue:[NSValue valueWithCGSize:CGSizeMake(decelerationRate,decelerationRate)] forKey:@"_decelerationFactor"];

        }
        @catch (NSException *exception) {
            // if they modify the way it works under us.
        }


    }
    return self;
}

shim 9 年前

有一个非常直接的方法。重写setter方法。

@interface UIArbitraryDeceleratingScrollView : UIScrollView

@property(nonatomic,assign) CGFloat decelerationRate;

@end

@implementation UIArbitraryDeceleratingScrollView

@synthesize decelerationRate = _decelerationRate;

- (void)setDecelerationRate:(CGFloat)dr
{
    [super setDecelerationRate:dr];
    _decelerationRate = dr;
}

@end

现在指定您想要的,例如:

_scroller.decelerationRate = (UIScrollViewDecelerationRateNormal+UIScrollViewDecelerationRateFast)/2.1;

Airsource Ltd 17 年前