The basic idea is from this stackoverflow question: http://stackoverflow.com/questions/18746929/using-auto-layout-in-uitableview-for-dynamic-cell-layouts-variable-row-heights (in Chinese).
So this library is designed to simplifies the height calculation and cache for auto layout views. And we provide two components in this library: MFViewHeightCache and UITableView+CellHeightCalculation.
MFViewHeightCache provides a simple way to calculate and cache the height of any kinds of auto layout views.
It basically adds a category method on UIView to calculates view's height, and then builds a cache on top of this method.
- (CGFloat)mf_heightForWidth:(CGFloat)width
withHeightCalculationView:(nullable UIView *)view
configuration:(nullable void(^)(void))configuration {
NSAssert(self.translatesAutoresizingMaskIntoConstraints, @"View must be auto layout enabled.");
if (configuration != nil) {
configuration();
}
[self setNeedsUpdateConstraints];
[self updateConstraintsIfNeeded];
[self setBounds:CGRectMake(0.0, 0.0, width, CGRectGetHeight(self.bounds))];
[self setNeedsLayout];
[self layoutIfNeeded];
return ceil([(view ?: self) systemLayoutSizeFittingSize:UILayoutFittingCompressedSize].height);
}The basically usage is cache the view first, then call the height calcualtion methods. For example:
// Let's say you have a heightCache property in your view controller.
@property (nonatomic, strong) MFViewHeightCache *heightCache;
// Cache view first.
- (MFViewHeightCache *)heightCache {
if (_heightCache == nil) {
_heightCache = [[MFViewHeightCache alloc] init];
BookCell *cell = (BookCell *)[[[NSBundle mainBundle]
loadNibNamed:NSStringFromClass([BookCell class])
owner:nil
options:nil]
firstObject];
[_heightCache cacheView:cell
withKey:NSStringFromClass([BookCell class])
heightCalculatedByView:cell.contentView];
}
return _heightCache;
}
// Then use heightCache to calculate and cache view's height.
__weak typeof(self) weakSelf = self;
const CGFloat height = [self.heightCache
heightForViewWithKey:NSStringFromClass([BookCell class])
width:CGRectGetWidth(tableView.bounds)
heightCacheKey:dataDict[@"ISBN"]
viewConfiguration:^(__kindof UIView * _Nonnull view) {
[weakSelf _configureCell:(BookCell *)view
withDict:dataDict];
}] + 1.0;Or if you don't need the cache, you can just use one of these UIView's category methods to calculate view's height:
- (CGFloat)mf_heightForWidth:(CGFloat)width;
- (CGFloat)mf_heightForWidth:(CGFloat)width
configuration:(nullable void(^)(void))configuration;
- (CGFloat)mf_heightForWidth:(CGFloat)width
withHeightCalculationView:(nullable UIView *)view
configuration:(nullable void(^)(void))configuration;To integrate MFViewHeightCache into your Xcode project using CocoaPods, specify it in your Podfile:
pod 'MFViewHeightCache', '~> 1.1.0'UITableView+CellHeightCalculation is an UITableView category that builds on top of MFViewHeightCache.
The APIs are very simple, basically all you have to do is in UITableViewDelegate -tableView:heightForRowAtIndexPath: method:
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
return [tableView mf_heightForCellWithIdentifier:@"cell reuse identifer" cellConfiguration:^(__kindof UITableViewCell * _Nonnull cell) {
//Configure cell with data, same as what you've done in "-tableView:cellForRowAtIndexPath:"
}];
}To integrate UITableView+CellHeightCalculation into your Xcode project using CocoaPods, specify it in your Podfile:
pod 'UITableView+CellHeightCalculation', '~> 1.1.1'UITableView+CellHeightCalculation is distributed under an MIT License.
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Copyright (c) 2016 Tinghui
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