我需要使用 nslayoutconstraints 以编程方式使用可视格式语言以及带项的约束来设计如下所示的自定义单元格。任何帮助将不胜感激。
` /* 初始化并分配产品名称 */ productName=[[UILabel alloc]init]; productName.font=[UIFont fontWithName:@"HelveticaNeue" size:17.0f]; self.productName.lineBreakMode = NSLineBreakByWordWrapping; self.productName.numberOfLines = 0; productName.translatesAutoresizingMaskIntoConstraints=NO; [self.contentView addSubview:productName];
/* Intialize and assign Product Option */
productOption=[[UILabel alloc]init];
productOption.translatesAutoresizingMaskIntoConstraints=NO;
productOption.font=[UIFont fontWithName:@"HelveticaNeue" size:13.0f];
productOption.textColor=[UIColor colorWithRed:128/255.0f green:128/255.0f blue:128/255.0f alpha:1.0f]; /* 808080 */
[self.contentView addSubview:productOption];
/* Intialize and assign Product Image */
productImageView=[[UIImageView alloc]init];
productImageView.translatesAutoresizingMaskIntoConstraints=NO;
productImageView.clipsToBounds=YES;
productImageView.contentMode=UIViewContentModeScaleAspectFill;
productImageView.layer.cornerRadius = 22.5;
productImageView.layer.masksToBounds = YES;
productImageView.layer.borderColor =[UIColor whiteColor].CGColor;
productImageView.layer.borderWidth = 1;
[self.contentView addSubview:productImageView];
/* Intialize and assign List icon Image */
listIconImage=[[UIImageView alloc]init];
listIconImage.translatesAutoresizingMaskIntoConstraints=NO;
listIconImage.image=[UIImage imageNamed:@"right-arrow.png"];
[self.contentView addSubview:listIconImage];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.productImageView
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.contentView
attribute:NSLayoutAttributeTop
multiplier:1.0
constant:7]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:productImageView
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:self.contentView
attribute:NSLayoutAttributeLeft
multiplier:1
constant:11.5]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.productImageView
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeWidth
multiplier:1.0
constant:45]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.productImageView
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeHeight
multiplier:1.0
constant:45]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.productName
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.productImageView
attribute:NSLayoutAttributeTrailing
multiplier:1.0
constant:10]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.productName
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.contentView
attribute:NSLayoutAttributeTop
multiplier:1.0
constant:5]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.productOption
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.productImageView
attribute:NSLayoutAttributeTrailing
multiplier:1.0
constant:10]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.productOption
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.productName
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:5]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.listIconImage
attribute:NSLayoutAttributeRight
relatedBy:NSLayoutRelationEqual
toItem:self.contentView
attribute:NSLayoutAttributeRight
multiplier:1.0
constant:-15.0f]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.listIconImage
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeHeight
multiplier:1.0
constant:20.0f]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.listIconImage
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeWidth
multiplier:1.0
constant:11.0f]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.listIconImage
attribute:NSLayoutAttributeCenterY
relatedBy:NSLayoutRelationEqual
toItem:self.contentView
attribute:NSLayoutAttributeCenterY
multiplier:1.0
constant:0]]; `
上面是我用来创建这个设计的代码。现在我正在为如何在 tableviewcontroller 中获取动态高度而苦苦挣扎。当我进入 heightForRowAtIndexPath 时，它总是返回 0。
感谢和问候 Sam.P