问如何编辑UIBlurEffect强度？

EN

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@interface UIVisualEffectView (Intensity)
@property (nonatomic) CGFloat intensity;
@end

NS_ASSUME_NONNULL_END

#import "UIVisualEffectView+Intensity.h"
#import <objc/message.h>

@interface UIVisualEffectView (Intensity)
@property (readonly) id backgroundHost; // _UIVisualEffectHost
@property (readonly) __kindof UIView *backdropView; // _UIVisualEffectBackdropView
@end

@implementation UIVisualEffectView (Intensity)

- (id)backgroundHost {
    id backgroundHost = ((id (*)(id, SEL))objc_msgSend)(self, NSSelectorFromString(@"_backgroundHost")); // _UIVisualEffectHost
    return backgroundHost;
}

- (__kindof UIView * _Nullable)backdropView {
    __kindof UIView *backdropView = ((__kindof UIView * (*)(id, SEL))objc_msgSend)(self.backgroundHost, NSSelectorFromString(@"contentView")); // _UIVisualEffectBackdropView
    return backdropView;
}

- (CGFloat)intensity {
    __kindof UIView *backdropView = self.backdropView; // _UIVisualEffectBackdropView
    __kindof CALayer *backdropLayer = ((__kindof CALayer * (*)(id, SEL))objc_msgSend)(backdropView, NSSelectorFromString(@"backdropLayer")); // UICABackdropLayer
    
    NSArray *filters = backdropLayer.filters;
    id _Nullable __block gaussianBlur = nil; // CAFilter
    
    [filters enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        if (![obj respondsToSelector:NSSelectorFromString(@"type")]) return;
        
        NSString *type = ((NSString * (*)(id, SEL))objc_msgSend)(obj, NSSelectorFromString(@"type"));
        
        if (![type isKindOfClass:[NSString class]]) return;
        
        if ([type isEqualToString:@"gaussianBlur"]) {
            gaussianBlur = obj;
            *stop = YES;
        }
    }];
    
    if (gaussianBlur == nil) return 0.0f;
    
    NSNumber * _Nullable inputRadius = [gaussianBlur valueForKeyPath:@"inputRadius"];
    
    if ((inputRadius == nil) || (![inputRadius isKindOfClass:[NSNumber class]])) return 0.0f;
    
    return [inputRadius floatValue];
}

- (void)setIntensity:(CGFloat)intensity {
    id descriptor = ((id (*)(id, SEL, id, BOOL))objc_msgSend)(self, NSSelectorFromString(@"_effectDescriptorForEffects:usage:"), @[self.effect], YES); // _UIVisualEffectDescriptor
    
    NSArray *filterEntries = ((NSArray * (*)(id, SEL))objc_msgSend)(descriptor, NSSelectorFromString(@"filterEntries")); // NSArray<_UIVisualEffectFilterEntry *>
    
    id _Nullable __block gaussianBlur = nil; // _UIVisualEffectFilterEntry
    
    [filterEntries enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        NSString *filterType = ((NSString * (*)(id, SEL))objc_msgSend)(obj, NSSelectorFromString(@"filterType"));
        
        if ([filterType isEqualToString:@"gaussianBlur"]) {
            gaussianBlur = obj;
            *stop = YES;
        }
    }];
    
    if (gaussianBlur == nil) return;
    
    NSMutableDictionary *requestedValues = [((NSDictionary * (*)(id, SEL))objc_msgSend)(gaussianBlur, NSSelectorFromString(@"requestedValues")) mutableCopy];

    if (![requestedValues.allKeys containsObject:@"inputRadius"]) {
        NSLog(@"Not supported effect.");
        return;
    }

    requestedValues[@"inputRadius"] = [NSNumber numberWithFloat:intensity];

    ((void (*)(id, SEL, NSDictionary *))objc_msgSend)(gaussianBlur, NSSelectorFromString(@"setRequestedValues:"), requestedValues);
    
    ((void (*)(id, SEL, id))objc_msgSend)(self.backgroundHost, NSSelectorFromString(@"setCurrentEffectDescriptor:"), descriptor);
    
    ((void (*)(id, SEL))objc_msgSend)(self.backdropView, NSSelectorFromString(@"applyRequestedFilterEffects"));
}

@end

let firstBlurView: UIVisualEffectView = .init(effect: UIBlurEffect(style: .dark))

// setter
firstBlurView.intensity = 7

// getter
print(firstBlurView.intensity) // 7.0