Не думаю, что вам удастся попытаться установить минимальное изображение дорожки.
Параметры - это полностью настраиваемый ползунок ...
или
Установитьминимальное изображение дорожки для четкого изображения, добавьте imageView с градиентным изображением за ползунком, растяните рамку imageView, чтобы соответствовать движению большого пальца.
Вот пример:
и код (просто отправная точка ... было бы гораздо лучше обернуть его в подкласс):
SliderTestViewController. ч
//
// SliderTestViewController.h
//
// Created by Don Mag on 10/31/19.
//
#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
@interface SliderTestViewController : UIViewController
@end
NS_ASSUME_NONNULL_END
SliderTestViewController.m
//
// SliderTestViewController.m
//
// Created by Don Mag on 10/31/19.
//
#import "SliderTestViewController.h"
#import "UIImage+Utils.h"
@interface SliderTestViewController ()
@property (strong, nonatomic) UIImageView *theFakeSliderTrackImageView;
@property (strong, nonatomic) UISlider *theSlider;
@property (strong, nonatomic) NSLayoutConstraint *imgWidthConstraint;
@end
@implementation SliderTestViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor whiteColor];
// instantiate a slider
_theSlider = [UISlider new];
// instantiate an image view to use as our custom / fake "left side" of the slider track
_theFakeSliderTrackImageView = [UIImageView new];
// we want the image to stretch
_theFakeSliderTrackImageView.contentMode = UIViewContentModeScaleToFill;
// create a horizontal gradient image to use for our "left side" of the slider track
// the image will be stretched... using a width of 128 seems reasonable
UIImage *gradImg = [UIImage gradientImageWithSize:CGSizeMake(128.0, 4.0) startColor:[UIColor blueColor] endColor:[UIColor redColor] startPoint:CGPointMake(0.0, 0.0) endPoint:CGPointMake(1.0, 0.0)];
// set the gradient image to our image view
_theFakeSliderTrackImageView.image = gradImg;
// create a clear image to use for the slider's min track image
UIImage *clearImg = [UIImage imageWithColor:[UIColor clearColor] size:CGSizeMake(1.0, 1.0)];
// set min track image to clear image
[_theSlider setMinimumTrackImage:clearImg forState:UIControlStateNormal];
// set max track image if desired
// [_theSlider setMaximumTrackImage:anImage forState:UIControlStateNormal];
_theFakeSliderTrackImageView.translatesAutoresizingMaskIntoConstraints = NO;
_theSlider.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:_theFakeSliderTrackImageView];
[self.view addSubview:_theSlider];
[NSLayoutConstraint activateConstraints:@[
// constrain the slider centerY with 20-pts leading / trailing
[_theSlider.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor],
[_theSlider.leadingAnchor constraintEqualToAnchor:self.view.leadingAnchor constant:20.0],
[_theSlider.trailingAnchor constraintEqualToAnchor:self.view.trailingAnchor constant:-20.0],
// constrain image view centerY to slider centerY
[_theFakeSliderTrackImageView.centerYAnchor constraintEqualToAnchor:_theSlider.centerYAnchor constant:0.0],
// constrain image view leading to slider leading
[_theFakeSliderTrackImageView.leadingAnchor constraintEqualToAnchor:_theSlider.leadingAnchor constant:0.0],
// image view height to 5-pts (adjust as desired)
[_theFakeSliderTrackImageView.heightAnchor constraintEqualToConstant:5.0],
]];
// init imageView width constraint to 0.0
_imgWidthConstraint = [_theFakeSliderTrackImageView.widthAnchor constraintEqualToConstant:0.0];
_imgWidthConstraint.active = YES;
[_theSlider addTarget:self action:@selector(sliderChanged:) forControlEvents:UIControlEventValueChanged];
}
- (void)viewDidLayoutSubviews {
[super viewDidLayoutSubviews];
[self updateSliderGradientImage];
}
- (void)updateSliderGradientImage {
// set "fake track" imageView width to origin.x of thumb rect (plus 2 for good measure)
CGRect trackRect = [_theSlider trackRectForBounds:_theSlider.bounds];
CGRect thumbRect = [_theSlider thumbRectForBounds:_theSlider.bounds trackRect:trackRect value:_theSlider.value];
_imgWidthConstraint.constant = thumbRect.origin.x + 2;
}
- (void)sliderChanged:(id)sender {
[self updateSliderGradientImage];
}
@end
UIImage + Utils.h
//
// UIImage+Utils.h
//
// Created by Don Mag on 10/31/19.
//
#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
@interface UIImage (Utils)
+ (nullable UIImage *)imageWithColor:(UIColor *)color size:(CGSize)size;
+ (nullable UIImage *)gradientImageWithSize:(CGSize)size startColor:(UIColor *)startColor endColor:(UIColor *)endColor startPoint:(CGPoint)startPoint endPoint:(CGPoint)endPoint;
@end
NS_ASSUME_NONNULL_END
UIImage + Utils.m
//
// UIImage+Utils.m
//
// Created by Don Mag on 10/31/19.
//
#import "UIImage+Utils.h"
@implementation UIImage (Utils)
+ (UIImage *)imageWithColor:(UIColor *)color size:(CGSize)size {
if (!color || size.height < 1 || size.width < 1)
return nil;
UIGraphicsImageRenderer *renderer = [[UIGraphicsImageRenderer alloc] initWithSize:size];
UIImage *image = [renderer imageWithActions:^(UIGraphicsImageRendererContext * _Nonnull context) {
[color setFill];
[context fillRect:renderer.format.bounds];
}];
return image;
}
+ (UIImage *)gradientImageWithSize:(CGSize)size startColor:(UIColor *)startColor endColor:(UIColor *)endColor startPoint:(CGPoint)startPoint endPoint:(CGPoint)endPoint {
if (!startColor || !endColor)
return nil;
CFArrayRef colors = (__bridge CFArrayRef) [NSArray arrayWithObjects:
(id)startColor.CGColor,
(id)endColor.CGColor,
nil];
CGGradientRef g = CGGradientCreateWithColors(nil, colors, nil);
startPoint.x *= size.width;
startPoint.y *= size.height;
endPoint.x *= size.width;
endPoint.y *= size.height;
UIGraphicsImageRenderer *renderer = [[UIGraphicsImageRenderer alloc] initWithSize:size];
UIImage *gradientImage = [renderer imageWithActions:^(UIGraphicsImageRendererContext * _Nonnull rendererContext) {
CGContextDrawLinearGradient(rendererContext.CGContext, g, startPoint, endPoint, kCGGradientDrawsAfterEndLocation);
}];
return gradientImage;
}
@end