DZNEmptyDataSet 是一个嵌入 UITableView／UICollectionView 超类的范畴（category），当视图没有要显示的内容时，它用于显示空数据集界面。
UIScrollView+ACSEmpty 是基本DZNEmptyDataSet原理进行封装的，同样适用于UITableView／UICollectionView / UIScrollView，使用起来也更简单
导入
1.手动导入下面的源代码
2.pod导入
pod 'ACSFramework/EmptyDataset'
使用
// 导入文件
#import "UIScrollView+WZQEmpty.h"
// EmptyFillView为自定义的空视图
EmptyFillView *emptyView = [[EmptyFillView alloc] initWithFrame:self.baseTableView.bounds];
emptyView.titleLabel.text = @"没有内容";
[emptyView.button setTitle:@"去看看其他" forState:UIControlStateNormal];
[emptyView.button addTarget:self action:@selector(popToBack) forControlEvents:UIControlEventTouchUpInside];
// self.baseTableView 为UITableView
self.baseTableView.emptyView = emptyView;
源代码
UIScrollView+ACSEmpty.h
#import <UIKit/UIKit.h>
@interface UIScrollView (ACSEmpty)
/** 空视图（tableview，colloctionview 为空时，显示此视图） */
@property (nonatomic, strong) UIView *acs_emptyView;
@end
UIScrollView+ACSEmpty.m
#import "UIScrollView+ACSEmpty.h"
#import <objc/runtime.h>
static char const * const kAcs_EmptyDataSetView = "acs_emptyDataSetView";
@implementation UIScrollView (ACSEmpty)
- (void)acs_reload {
if (![self acs_canDisplay]) {
return;
}
if (!self.acs_emptyView) {
return;
}
if ([self acs_itemsCount] == 0) {
if (!self.acs_emptyView.superview) {
if (([self isKindOfClass:[UITableView class]] || [self isKindOfClass:[UICollectionView class]]) && self.subviews.count > 1) {
[self insertSubview:self.acs_emptyView atIndex:0];
}
else {
[self addSubview:self.acs_emptyView];
}
}
}else {
[self.acs_emptyView removeFromSuperview];
}
}
- (BOOL)acs_canDisplay {
if ([self isKindOfClass:[UITableView class]] || [self isKindOfClass:[UICollectionView class]] || [self isKindOfClass:[UIScrollView class]]) {
if (self.acs_emptyView) {
return YES;
}
}
return NO;
}
- (NSInteger)acs_itemsCount {
NSInteger items = 0;
// UIScollView doesn't respond to 'dataSource' so let's exit
if (![self respondsToSelector:@selector(dataSource)]) {
return items;
}
// UITableView support
if ([self isKindOfClass:[UITableView class]]) {
UITableView *tableView = (UITableView *)self;
id <UITableViewDataSource> dataSource = tableView.dataSource;
NSInteger sections = 1;
if (dataSource && [dataSource respondsToSelector:@selector(numberOfSectionsInTableView:)]) {
sections = [dataSource numberOfSectionsInTableView:tableView];
}
if (dataSource && [dataSource respondsToSelector:@selector(tableView:numberOfRowsInSection:)]) {
for (NSInteger section = 0; section < sections; section++) {
items += [dataSource tableView:tableView numberOfRowsInSection:section];
}
}
}
// UICollectionView support
else if ([self isKindOfClass:[UICollectionView class]]) {
UICollectionView *collectionView = (UICollectionView *)self;
id <UICollectionViewDataSource> dataSource = collectionView.dataSource;
NSInteger sections = 1;
if (dataSource && [dataSource respondsToSelector:@selector(numberOfSectionsInCollectionView:)]) {
sections = [dataSource numberOfSectionsInCollectionView:collectionView];
}
if (dataSource && [dataSource respondsToSelector:@selector(collectionView:numberOfItemsInSection:)]) {
for (NSInteger section = 0; section < sections; section++) {
items += [dataSource collectionView:collectionView numberOfItemsInSection:section];
}
}
}
return items;
}
#pragma mark - Getters &Setter (Public)
- (UIView *)acs_emptyView {
UIView *view = objc_getAssociatedObject(self, kAcs_EmptyDataSetView);
return view;
}
- (void)setAcs_emptyView:(UIView *)emptyView {
objc_setAssociatedObject(self, kAcs_EmptyDataSetView,emptyView, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
[self swizzleIfPossible:@selector(reloadData)];
}
#pragma mark - Method Swizzling
static NSMutableDictionary *_impLookupTable;
static NSString *const DZNSwizzleInfoPointerKey = @"pointer";
static NSString *const DZNSwizzleInfoOwnerKey = @"owner";
static NSString *const DZNSwizzleInfoSelectorKey = @"selector";
// Based on Bryce Buchanan's swizzling technique http://blog.newrelic.com/2014/04/16/right-way-to-swizzle/
// And Juzzin's ideas https://github.com/juzzin/JUSEmptyViewController
void dzn_original_implementation(id self, SEL _cmd)
{
// Fetch original implementation from lookup table
Class baseClass = acs_baseClassToSwizzleForTarget(self);
NSString *key = acs_implementationKey(baseClass, _cmd);
NSDictionary *swizzleInfo = [_impLookupTable objectForKey:key];
NSValue *impValue = [swizzleInfo valueForKey:DZNSwizzleInfoPointerKey];
IMP impPointer = [impValue pointerValue];
// We then inject the additional implementation for reloading the empty dataset
// Doing it before calling the original implementation does update the 'isEmptyDataSetVisible' flag on time.
[self acs_reload];
// If found, call original implementation
if (impPointer) {
((void(*)(id,SEL))impPointer)(self,_cmd);
}
}
NSString *acs_implementationKey(Class class, SEL selector)
{
if (!class || !selector) {
return nil;
}
NSString *className = NSStringFromClass([class class]);
NSString *selectorName = NSStringFromSelector(selector);
return [NSString stringWithFormat:@"%@_%@",className,selectorName];
}
Class acs_baseClassToSwizzleForTarget(id target)
{
if ([target isKindOfClass:[UITableView class]]) {
return [UITableView class];
}
else if ([target isKindOfClass:[UICollectionView class]]) {
return [UICollectionView class];
}
else if ([target isKindOfClass:[UIScrollView class]]) {
return [UIScrollView class];
}
return nil;
}
- (void)swizzleIfPossible:(SEL)selector
{
// Check if the target responds to selector
if (![self respondsToSelector:selector]) {
return;
}
// Create the lookup table
if (!_impLookupTable) {
_impLookupTable = [[NSMutableDictionary alloc] initWithCapacity:3]; // 3 represent the supported base classes
}
// We make sure that setImplementation is called once per class kind, UITableView or UICollectionView.
for (NSDictionary *info in [_impLookupTable allValues]) {
Class class = [info objectForKey:DZNSwizzleInfoOwnerKey];
NSString *selectorName = [info objectForKey:DZNSwizzleInfoSelectorKey];
if ([selectorName isEqualToString:NSStringFromSelector(selector)]) {
if ([self isKindOfClass:class]) {
return;
}
}
}
Class baseClass = acs_baseClassToSwizzleForTarget(self);
NSString *key = acs_implementationKey(baseClass, selector);
NSValue *impValue = [[_impLookupTable objectForKey:key] valueForKey:DZNSwizzleInfoPointerKey];
// If the implementation for this class already exist, skip!!
if (impValue || !key || !baseClass) {
return;
}
// Swizzle by injecting additional implementation
Method method = class_getInstanceMethod(baseClass, selector);
IMP dzn_newImplementation = method_setImplementation(method, (IMP)dzn_original_implementation);
// Store the new implementation in the lookup table
NSDictionary *swizzledInfo = @{DZNSwizzleInfoOwnerKey: baseClass,
DZNSwizzleInfoSelectorKey: NSStringFromSelector(selector),
DZNSwizzleInfoPointerKey: [NSValue valueWithPointer:dzn_newImplementation]};
[_impLookupTable setObject:swizzledInfo forKey:key];
}
@end
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