uni-app provides the functionality to obtain geographic location and display maps primarily through the uni.getLocation API and the map component. The uni.getLocation API can retrieve the device's current position, including latitude, longitude, altitude, and other information, supporting multiple coordinate types. The map component, based on native platform maps, offers rich features such as displaying markers, drawing routes, and adding overlays. The article details the basic usage methods, parameter configuration, event handling, and advanced functionalities like route drawing and circular overlays. It also emphasizes performance optimization, handling platform differences, and practical business scenarios such as displaying nearby merchants and recording trajectories. Finally, it mentions that third-party plugins can be used to extend map capabilities and enhance the application experience.
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The `uni.getSystemInfo` is a native API provided by Uniapp for retrieving device information, including device model, operating system version, screen dimensions, window dimensions, pixel ratio, and other detailed parameters. Developers can leverage this information for responsive layouts, device adaptation, or feature detection. The article provides a detailed breakdown of the returned parameters, such as device brand, model, pixel ratio, screen width and height, status bar height, etc., along with practical application scenarios like responsive layout adaptation, platform-specific feature implementation, and safe area handling. It also introduces synchronous retrieval methods, performance optimization tips, common issue resolutions, and advanced techniques such as listening for device changes, integrating with CSS variables, and cross-platform compatibility handling. Finally, it offers comprehensive application examples in real-world projects and debugging techniques to help developers better utilize this API for development.
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The `uni.uploadFile` in UniApp is an API used to upload local resources to a server, encapsulating the underlying upload interfaces of platforms like WeChat Mini Programs and H5 to provide a unified calling method. The upload process supports operations such as progress monitoring and cancellation. Basic usage involves selecting a file and uploading it by specifying a URL, file path, and other parameters. In actual development, common scenarios include multi-file uploads and uploads with progress display. The `uni.downloadFile` is used to download file resources from the network to a local temporary path, often requiring coordination with `saveFile` to store the complete file. The operational workflow includes downloading, saving, and handling results. Common issues involve large file chunked uploads, file renaming, and cross-platform compatibility. Security considerations include file type restrictions, size checks, and security validation for downloaded files. Performance optimizations include concurrent upload control and queue management.
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The uni-app framework provides data caching functionality through the `uni.setStorage` method, enabling local storage that supports various data types, including strings, numbers, booleans, objects, and arrays. The storage methods are divided into asynchronous and synchronous operations. Cache expiration can be managed using timestamps. Advanced features such as batch operations, data encryption, and cross-page sharing are also introduced. Performance optimization recommendations include avoiding frequent writes, setting reasonable cache sizes, and regularly cleaning up unused caches. Finally, practical application scenarios are listed, such as maintaining user login states, saving form drafts, persisting app configurations, and solutions to common issues.
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The uni-request API in the uni-app framework is used for cross-platform HTTP requests, supporting methods like GET and POST. By configuring parameters such as URL, method, data, and headers, it initiates requests. The `success` callback handles response data, `fail` handles errors, and `complete` executes regardless of success or failure. It supports Promise-style usage and can be combined with async/await. It offers timeout settings and file upload functionality. Interceptor-like effects can be achieved through encapsulation. Cross-origin issues can be resolved via proxies or CORS. Practical applications include user login, with complete examples provided. Performance optimization suggestions include caching, merging requests, request cancellation, and data compression.
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uni-app provides multiple routing navigation methods. The basic method is `uni.navigateTo`, which retains the current page and navigates to the specified page. The target page retrieves parameters via `onLoad`. Special routing methods include: - `uni.redirectTo`: Closes the current page and navigates. - `uni.reLaunch`: Closes all pages and navigates. - `uni.switchTab`: Navigates to a tabBar page (tabBar must be configured in `pages.json` with special restrictions; `navigateTo` cannot be used). Routing parameter passing can be achieved via URL global variables or Vuex. Routing interception can be implemented by overriding methods for permission control. Multiple routing animation effects are supported. Routing stack information can be retrieved, and titles can be dynamically modified. Routing changes can be monitored. Common issues include: - Page refresh on return. - Page stack limitations. - tabBar red dot notifications. Cross-platform routing has differences and requires compatibility handling. Performance optimization techniques include: - Preloading. - Subpackage loading. - Lazy loading. Routing is closely related to the page lifecycle. Parameter handling requires attention to security validation and encoding/decoding. Advanced communication patterns include EventBus and Vuex. Routing hooks can be simulated by overriding methods or using page-level hooks.
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uni-app provides a variety of form components for building user interaction interfaces, including input, checkbox, picker, and more. The **input** component is used to receive user-entered text and supports types such as text, number, and password. **Checkbox** is used for multiple-selection scenarios and can be used individually or in combination. **Picker** is a selector component that supports standard selectors, time pickers, date pickers, and more. **Radio** is used for single-selection scenarios, typically used in conjunction with a **radio-group**. **Switch** is a sliding toggle component for switching between two states. **Textarea** is a multi-line text input component suitable for large amounts of text. **Slider** is a sliding selector for choosing values within a specified range. The **form** component is used to group multiple form components and submit data uniformly. Form validation is a crucial step and can be implemented in various ways. These components each have unique features to meet different data collection needs in various scenarios.
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The uni-app built-in components provide rich cross-platform development capabilities without worrying about underlying differences. The view component is the most basic container, supporting flex layout and event handling. The scroll-view component enables scrollable view areas, supporting horizontal and vertical scrolling as well as scrolling to specified positions. The swiper component is used for carousel effects, supporting autoplay and vertical sliding. The text component is specifically designed for displaying text, supporting long-press selection and copy functionality. The image component handles image display, offering various scaling modes and load failure handling. The navigator component enables page navigation, supporting multiple navigation methods and parameter passing. The button component provides various styles and open capabilities, supporting loading states. The input component handles user input, supporting multiple input types and confirmation events. The checkbox and radio components implement multi-selection and single-selection functions, respectively. These components cover most development needs.
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In uni-app development, the rpx unit and Flex layout are core technologies for achieving responsive design and flexible page structures. The rpx unit adaptively scales based on screen width, making it ideal for multi-size screen adaptation. When the design draft is 750px, 1rpx equals 1px; for non-750px design drafts, proportional conversion is required, but caution is needed with small fonts and thin borders. Flex layout enables complex structures through container and item properties, with commonly used attributes including flex-direction, justify-content, align-items, etc. Combined with rpx, it can build adaptive grids, navigation bars, and other layouts. Native components require upx2px conversion for older versions, while Flex compatibility is automatically handled by the compiler. Complex layouts can also be achieved by combining absolute positioning.
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In UniApp, conditional rendering is primarily achieved through the `v-if`, `v-else-if`, `v-else`, and `v-show` directives. `v-if` destroys or recreates DOM elements based on conditions, while `v-show` toggles the CSS `display` property. For list rendering, the `v-for` directive is used to iterate over arrays or objects. Each node must be assigned a unique `key` attribute so Vue can identify nodes. When updating arrays, mutation methods must be used to trigger view updates. When using `v-for` on components, data must be passed via `props`. Conditional rendering and list rendering are often combined. For performance optimization, it is recommended to avoid complex expressions in `v-for`, freeze large lists, and consider virtual scrolling techniques. Common issues include the priority conflict between `v-if` and `v-for`, dynamically filtering or sorting lists, and handling cross-platform differences.
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