FTGViewPool

FTGViewPool

// UIView+FTGAdditions.h
- (NSString *)ftg_identifier;
- (void)ftg_setIdentifier:(NSString *)identifier;

// UIVIew+FTGAdditions.m
- (NSString *)ftg_identifier {
    return (NSString *)objc_getAssociatedObject(self, @selector(ftg_identifier));
}

- (void)ftg_setIdentifier:(NSString *)identifier {
    objc_setAssociatedObject(self, @selector(ftg_identifier), identifier, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

// FTGViewPool.h
@protocol FTGViewPoolDelegate <NSObject>

- (UIView *)viewPoolRequestViewWithIdentifier:(NSString *)identifier;

@end

@interface FTGViewPool : NSObject

@property (nonatomic, weak) id<FTGViewPoolDelegate> delegate;

- (UIView *)dequeueView;

@end

// FTGViewPool.m
@interface FTGViewPool ()

@property (nonatomic, strong) NSMutableArray *views;

@end

@implementation FTGViewPool

#pragma mark - Life Cycle
- (instancetype)init {
    self = [super init];
    if (self) {
        _views = [NSMutableArray array];
    }

    return self;
}

#pragma mark - Public Interface
- (UIView *)dequeueViewWithIdentifier:(NSString *)identifier {
    // Find the first view that is not in any hierarchy
    for (UIView *view in self.views) {
        if ([self isViewAvailable:view identifier:identifier]) {
            return view;
        }
    }

    // Else request new view
    UIView *view = [self requestViewWithIdentifier:identifier];
    [view ftg_setIdentifier:identifier];
    [self.views addObject:view];
    return view;
}

#pragma mark - Helper
- (BOOL)isViewAvailable:(UIView *)view identifier:(NSString *)identifier {
    return YES;
}

#pragma mark - Delegate
- (UIView *)requestViewWithIdentifier:(NSString *)identifier {
    if ([self.delegate respondsToSelector:@selector(viewPoolRequestViewWithIdentifier:)]) {
        return [self.delegate viewPoolRequestViewWithIdentifier:identifier];
    }

    return nil;
}

@end

// Usage
#pragma mark - FTGViewPoolDelegate
- (UIView *)viewPoolRequestViewWithIdentifier:(NSString *)identifier {
    if ([identifier isEqualToString:kSetPoint]) {
        return [self verticalLineImageView];
    }

    return [self blankImageView];
}

#pragma mark - ImageView Factory
- (UIImageView *)blankImageView {
    return [[UIImageView alloc] init];
}

- (UIImageView *)verticalLineImageView {
    UIImageView *imageView = [[UIImageView alloc] init];
    [imageView setImage:[UIImage imageNamed:@"verticle_line"]];
    return imageView;
}