自定义UIPickerView,带有三个组件,每个组件在选择指示器上显示标签

Question

在我的应用程序中,我正在尝试制作UIPickerView包含三个组件(天,小时和分钟)的自定义.我已经使用三个组件制作了自定义选取器.现在我陷入了如何将标签添加到选择指示器的位置,该指示器显示了几天,几小时或几分钟的组件.

我已经浏览了本网站上发布的每一个链接或问题,但没有人帮助过我.

我正在尝试实现像这样的图像

任何人都可以建议我如何实现这一目标？

Answer 1

这就是我实现这一目标的方法......我在我发现的一些代码的帮助下制作了我的自定义 PickerView ......

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在.h文件中：

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//  LabeledPickerView.h\n//  LabeledPickerView\n\n#import <UIKit/UIKit.h>\n\n@interface LabeledPickerView : UIPickerView\n\n{\n    NSMutableDictionary *labels;\n}\n\n/** Adds the label for the given component. */\n-(void)addLabel:(NSString *)labeltext forComponent:(NSUInteger)component forLongestString:(NSString *)longestString;\n@end\n

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并在 .m 文件中...

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//  LabeledPickerView.m\n//  LabeledPickerView\n\n#import "LabeledPickerView.h"\n\n@implementation LabeledPickerView\n\n/** loading programmatically */\n- (id)initWithFrame:(CGRect)aRect {\n    if (self = [super initWithFrame:aRect]) {\n        labels = [[NSMutableDictionary alloc] initWithCapacity:3];\n    }\n    return self;\n}\n\n/** loading from nib */\n- (id)initWithCoder:(NSCoder *)coder {\n    if (self = [super initWithCoder:coder]) {\n        labels = [[NSMutableDictionary alloc] initWithCapacity:3];\n    }\n    return self;\n}\n\n- (void) dealloc\n{\n    [labels release];\n    [super dealloc];\n}\n\n#pragma mark Labels\n\n// Add labelText to our array but also add what will be the longest label we will use in updateLabel\n// If you do not plan to update label then the longestString should be the same as the labelText\n// This way we can initially size our label to the longest width and we get the same effect Apple uses\n\n-(void)addLabel:(NSString *)labeltext forComponent:(NSUInteger)component forLongestString:(NSString *)longestString {\n    [labels setObject:labeltext forKey:[NSNumber numberWithInt:component]];\n\n    NSString *keyName = [NSString stringWithFormat:@"%@_%@", @"longestString", [NSNumber numberWithInt:component]];\n\n    if(!longestString) {\n        longestString = labeltext;\n    }\n\n    [labels setObject:longestString forKey:keyName];\n}\n\n//\n- (void) updateLabel:(NSString *)labeltext forComponent:(NSUInteger)component {\n\n    UILabel *theLabel = (UILabel*)[self viewWithTag:component + 1];\n\n    // Update label if it doesn\xc3\xa2\xe2\x82\xac\xe2\x84\xa2t match current label\n    if (![theLabel.text isEqualToString:labeltext]) {\n\n        NSString *keyName = [NSString stringWithFormat:@"%@_%@", @"longestString", [NSNumber numberWithInt:component]];\n        NSString *longestString = [labels objectForKey:keyName];\n\n        // Update label array with our new string value\n        [self addLabel:labeltext forComponent:component forLongestString:longestString];\n\n        // change label during fade out/in\n        [UIView beginAnimations:nil context:NULL];\n        [UIView setAnimationDuration:0.75];\n        [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];\n        theLabel.alpha = 0.00;\n        theLabel.text = labeltext;\n        theLabel.alpha = 1.00;\n        [UIView commitAnimations];\n    }\n\n}\n\n/**\n Adds the labels to the view, below the selection indicator glass-thingy.\n The labels are aligned to the right side of the wheel.\n The delegate is responsible for providing enough width for both the value and the label.\n */\n- (void)didMoveToWindow {\n    // exit if view is removed from the window or there are no labels.\n    if (!self.window || [labels count] == 0)\n        return;\n\n    UIFont *labelfont = [UIFont boldSystemFontOfSize:15];\n\n    // find the width of all the wheels combined\n    CGFloat widthofwheels = 0;\n    for (int i=0; i<self.numberOfComponents; i++) {\n        widthofwheels += [self rowSizeForComponent:i].width;\n    }\n\n    // find the left side of the first wheel.\n    // seems like a misnomer, but that will soon be corrected.\n    CGFloat rightsideofwheel = (self.frame.size.width - widthofwheels) / 2;\n\n    // cycle through all wheels\n    for (int component=0; component<self.numberOfComponents; component++) {\n        // find the right side of the wheel\n        rightsideofwheel += [self rowSizeForComponent:component].width;\n\n        // get the text for the label.\n        // move on to the next if there is no label for this wheel.\n        NSString *text = [labels objectForKey:[NSNumber numberWithInt:component]];\n        if (text) {\n\n            // set up the frame for the label using our longestString length\n            NSString *keyName = [NSString stringWithFormat:@"%@_%@", [NSString stringWithString:@"longestString"], [NSNumber numberWithInt:component]];\n            NSString *longestString = [labels objectForKey:keyName];\n            CGRect frame;\n            frame.size = [longestString sizeWithFont:labelfont];\n\n            // center it vertically\n            frame.origin.y = (self.frame.size.height / 2) - (frame.size.height / 2) - 0.5;\n\n            // align it to the right side of the wheel, with a margin.\n            // use a smaller margin for the rightmost wheel.\n            frame.origin.x = rightsideofwheel - frame.size.width -\n            (component == self.numberOfComponents - 1 ? 5 : 7);\n\n            // set up the label. If label already exists, just get a reference to it\n            BOOL addlabelView = NO;\n            UILabel *label = (UILabel*)[self viewWithTag:component + 1];\n            if(!label) {\n                label = [[[UILabel alloc] initWithFrame:frame] autorelease];\n                addlabelView = YES;\n            }\n\n            label.text = text;\n            label.font = labelfont;\n            label.backgroundColor = [UIColor clearColor];\n            label.shadowColor = [UIColor whiteColor];\n            label.shadowOffset = CGSizeMake(0,1);\n\n            // Tag cannot be 0 so just increment component number to esnure we get a positive\n            // NB update/remove Label methods are aware of this incrementation!\n            label.tag = component + 1;\n\n            if(addlabelView) {\n                /*\n                 and now for the tricky bit: adding the label to the view.\n                 kind of a hack to be honest, might stop working if Apple decides to\n                 change the inner workings of the UIPickerView.\n                 */\n                if (self.showsSelectionIndicator) {\n                    // if this is the last wheel, add label as the third view from the top\n                    if (component==self.numberOfComponents-1)\n                        [self insertSubview:label atIndex:[self.subviews count]-3];\n                    // otherwise add label as the 5th, 10th, 15th etc view from the top\n                    else\n                        [self insertSubview:label aboveSubview:[self.subviews objectAtIndex:5*(component+1)]];\n                } else\n                    // there is no selection indicator, so just add it to the top\n                    [self addSubview:label];\n\n            }\n\n            if ([self.delegate respondsToSelector:@selector(pickerView:didSelectRow:inComponent:)])\n                [self.delegate pickerView:self didSelectRow:[self selectedRowInComponent:component] inComponent:component];\n        }\n\n    }\n\n}\n

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并使用标签文本和组件标签调用此 addLabel: 方法，就是这样..!!

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